Loading Documentation/sound/alsa/timestamping.txt 0 → 100644 +200 −0 Original line number Original line Diff line number Diff line The ALSA API can provide two different system timestamps: - Trigger_tstamp is the system time snapshot taken when the .trigger callback is invoked. This snapshot is taken by the ALSA core in the general case, but specific hardware may have synchronization capabilities or conversely may only be able to provide a correct estimate with a delay. In the latter two cases, the low-level driver is responsible for updating the trigger_tstamp at the most appropriate and precise moment. Applications should not rely solely on the first trigger_tstamp but update their internal calculations if the driver provides a refined estimate with a delay. - tstamp is the current system timestamp updated during the last event or application query. The difference (tstamp - trigger_tstamp) defines the elapsed time. The ALSA API provides reports two basic pieces of information, avail and delay, which combined with the trigger and current system timestamps allow for applications to keep track of the 'fullness' of the ring buffer and the amount of queued samples. The use of these different pointers and time information depends on the application needs: - 'avail' reports how much can be written in the ring buffer - 'delay' reports the time it will take to hear a new sample after all queued samples have been played out. When timestamps are enabled, the avail/delay information is reported along with a snapshot of system time. Applications can select from CLOCK_REALTIME (NTP corrections including going backwards), CLOCK_MONOTONIC (NTP corrections but never going backwards), CLOCK_MONOTIC_RAW (without NTP corrections) and change the mode dynamically with sw_params The ALSA API also provide an audio_tstamp which reflects the passage of time as measured by different components of audio hardware. In ascii-art, this could be represented as follows (for the playback case): --------------------------------------------------------------> time ^ ^ ^ ^ ^ | | | | | analog link dma app FullBuffer time time time time time | | | | | |< codec delay >|<--hw delay-->|<queued samples>|<---avail->| |<----------------- delay---------------------->| | |<----ring buffer length---->| The analog time is taken at the last stage of the playback, as close as possible to the actual transducer The link time is taken at the output of the SOC/chipset as the samples are pushed on a link. The link time can be directly measured if supported in hardware by sample counters or wallclocks (e.g. with HDAudio 24MHz or PTP clock for networked solutions) or indirectly estimated (e.g. with the frame counter in USB). The DMA time is measured using counters - typically the least reliable of all measurements due to the bursty natured of DMA transfers. The app time corresponds to the time tracked by an application after writing in the ring buffer. The application can query what the hardware supports, define which audio time it wants reported by selecting the relevant settings in audio_tstamp_config fields, get an estimate of the timestamp accuracy. It can also request the delay-to-analog be included in the measurement. Direct access to the link time is very interesting on platforms that provide an embedded DSP; measuring directly the link time with dedicated hardware, possibly synchronized with system time, removes the need to keep track of internal DSP processing times and latency. In case the application requests an audio tstamp that is not supported in hardware/low-level driver, the type is overridden as DEFAULT and the timestamp will report the DMA time based on the hw_pointer value. For backwards compatibility with previous implementations that did not provide timestamp selection, with a zero-valued COMPAT timestamp type the results will default to the HDAudio wall clock for playback streams and to the DMA time (hw_ptr) in all other cases. The audio timestamp accuracy can be returned to user-space, so that appropriate decisions are made: - for dma time (default), the granularity of the transfers can be inferred from the steps between updates and in turn provide information on how much the application pointer can be rewound safely. - the link time can be used to track long-term drifts between audio and system time using the (tstamp-trigger_tstamp)/audio_tstamp ratio, the precision helps define how much smoothing/low-pass filtering is required. The link time can be either reset on startup or reported as is (the latter being useful to compare progress of different streams - but may require the wallclock to be always running and not wrap-around during idle periods). If supported in hardware, the absolute link time could also be used to define a precise start time (patches WIP) - including the delay in the audio timestamp may counter-intuitively not increase the precision of timestamps, e.g. if a codec includes variable-latency DSP processing or a chain of hardware components the delay is typically not known with precision. The accuracy is reported in nanosecond units (using an unsigned 32-bit word), which gives a max precision of 4.29s, more than enough for audio applications... Due to the varied nature of timestamping needs, even for a single application, the audio_tstamp_config can be changed dynamically. In the STATUS ioctl, the parameters are read-only and do not allow for any application selection. To work around this limitation without impacting legacy applications, a new STATUS_EXT ioctl is introduced with read/write parameters. ALSA-lib will be modified to make use of STATUS_EXT and effectively deprecate STATUS. The ALSA API only allows for a single audio timestamp to be reported at a time. This is a conscious design decision, reading the audio timestamps from hardware registers or from IPC takes time, the more timestamps are read the more imprecise the combined measurements are. To avoid any interpretation issues, a single (system, audio) timestamp is reported. Applications that need different timestamps will be required to issue multiple queries and perform an interpolation of the results In some hardware-specific configuration, the system timestamp is latched by a low-level audio subsytem, and the information provided back to the driver. Due to potential delays in the communication with the hardware, there is a risk of misalignment with the avail and delay information. To make sure applications are not confused, a driver_timestamp field is added in the snd_pcm_status structure; this timestamp shows when the information is put together by the driver before returning from the STATUS and STATUS_EXT ioctl. in most cases this driver_timestamp will be identical to the regular system tstamp. Examples of typestamping with HDaudio: 1. DMA timestamp, no compensation for DMA+analog delay $ ./audio_time -p --ts_type=1 playback: systime: 341121338 nsec, audio time 342000000 nsec, systime delta -878662 playback: systime: 426236663 nsec, audio time 427187500 nsec, systime delta -950837 playback: systime: 597080580 nsec, audio time 598000000 nsec, systime delta -919420 playback: systime: 682059782 nsec, audio time 683020833 nsec, systime delta -961051 playback: systime: 852896415 nsec, audio time 853854166 nsec, systime delta -957751 playback: systime: 937903344 nsec, audio time 938854166 nsec, systime delta -950822 2. DMA timestamp, compensation for DMA+analog delay $ ./audio_time -p --ts_type=1 -d playback: systime: 341053347 nsec, audio time 341062500 nsec, systime delta -9153 playback: systime: 426072447 nsec, audio time 426062500 nsec, systime delta 9947 playback: systime: 596899518 nsec, audio time 596895833 nsec, systime delta 3685 playback: systime: 681915317 nsec, audio time 681916666 nsec, systime delta -1349 playback: systime: 852741306 nsec, audio time 852750000 nsec, systime delta -8694 3. link timestamp, compensation for DMA+analog delay $ ./audio_time -p --ts_type=2 -d playback: systime: 341060004 nsec, audio time 341062791 nsec, systime delta -2787 playback: systime: 426242074 nsec, audio time 426244875 nsec, systime delta -2801 playback: systime: 597080992 nsec, audio time 597084583 nsec, systime delta -3591 playback: systime: 682084512 nsec, audio time 682088291 nsec, systime delta -3779 playback: systime: 852936229 nsec, audio time 852940916 nsec, systime delta -4687 playback: systime: 938107562 nsec, audio time 938112708 nsec, systime delta -5146 Example 1 shows that the timestamp at the DMA level is close to 1ms ahead of the actual playback time (as a side time this sort of measurement can help define rewind safeguards). Compensating for the DMA-link delay in example 2 helps remove the hardware buffering abut the information is still very jittery, with up to one sample of error. In example 3 where the timestamps are measured with the link wallclock, the timestamps show a monotonic behavior and a lower dispersion. Example 3 and 4 are with USB audio class. Example 3 shows a high offset between audio time and system time due to buffering. Example 4 shows how compensating for the delay exposes a 1ms accuracy (due to the use of the frame counter by the driver) Example 3: DMA timestamp, no compensation for delay, delta of ~5ms $ ./audio_time -p -Dhw:1 -t1 playback: systime: 120174019 nsec, audio time 125000000 nsec, systime delta -4825981 playback: systime: 245041136 nsec, audio time 250000000 nsec, systime delta -4958864 playback: systime: 370106088 nsec, audio time 375000000 nsec, systime delta -4893912 playback: systime: 495040065 nsec, audio time 500000000 nsec, systime delta -4959935 playback: systime: 620038179 nsec, audio time 625000000 nsec, systime delta -4961821 playback: systime: 745087741 nsec, audio time 750000000 nsec, systime delta -4912259 playback: systime: 870037336 nsec, audio time 875000000 nsec, systime delta -4962664 Example 4: DMA timestamp, compensation for delay, delay of ~1ms $ ./audio_time -p -Dhw:1 -t1 -d playback: systime: 120190520 nsec, audio time 120000000 nsec, systime delta 190520 playback: systime: 245036740 nsec, audio time 244000000 nsec, systime delta 1036740 playback: systime: 370034081 nsec, audio time 369000000 nsec, systime delta 1034081 playback: systime: 495159907 nsec, audio time 494000000 nsec, systime delta 1159907 playback: systime: 620098824 nsec, audio time 619000000 nsec, systime delta 1098824 playback: systime: 745031847 nsec, audio time 744000000 nsec, systime delta 1031847 include/sound/pcm.h +64 −2 Original line number Original line Diff line number Diff line Loading @@ -60,6 +60,9 @@ struct snd_pcm_hardware { struct snd_pcm_substream; struct snd_pcm_substream; struct snd_pcm_audio_tstamp_config; /* definitions further down */ struct snd_pcm_audio_tstamp_report; struct snd_pcm_ops { struct snd_pcm_ops { int (*open)(struct snd_pcm_substream *substream); int (*open)(struct snd_pcm_substream *substream); int (*close)(struct snd_pcm_substream *substream); int (*close)(struct snd_pcm_substream *substream); Loading @@ -71,8 +74,10 @@ struct snd_pcm_ops { int (*prepare)(struct snd_pcm_substream *substream); int (*prepare)(struct snd_pcm_substream *substream); int (*trigger)(struct snd_pcm_substream *substream, int cmd); int (*trigger)(struct snd_pcm_substream *substream, int cmd); snd_pcm_uframes_t (*pointer)(struct snd_pcm_substream *substream); snd_pcm_uframes_t (*pointer)(struct snd_pcm_substream *substream); int (*wall_clock)(struct snd_pcm_substream *substream, int (*get_time_info)(struct snd_pcm_substream *substream, struct timespec *audio_ts); struct timespec *system_ts, struct timespec *audio_ts, struct snd_pcm_audio_tstamp_config *audio_tstamp_config, struct snd_pcm_audio_tstamp_report *audio_tstamp_report); int (*copy)(struct snd_pcm_substream *substream, int channel, int (*copy)(struct snd_pcm_substream *substream, int channel, snd_pcm_uframes_t pos, snd_pcm_uframes_t pos, void __user *buf, snd_pcm_uframes_t count); void __user *buf, snd_pcm_uframes_t count); Loading Loading @@ -281,6 +286,58 @@ struct snd_pcm_hw_constraint_ranges { struct snd_pcm_hwptr_log; struct snd_pcm_hwptr_log; /* * userspace-provided audio timestamp config to kernel, * structure is for internal use only and filled with dedicated unpack routine */ struct snd_pcm_audio_tstamp_config { /* 5 of max 16 bits used */ u32 type_requested:4; u32 report_delay:1; /* add total delay to A/D or D/A */ }; static inline void snd_pcm_unpack_audio_tstamp_config(__u32 data, struct snd_pcm_audio_tstamp_config *config) { config->type_requested = data & 0xF; config->report_delay = (data >> 4) & 1; } /* * kernel-provided audio timestamp report to user-space * structure is for internal use only and read by dedicated pack routine */ struct snd_pcm_audio_tstamp_report { /* 6 of max 16 bits used for bit-fields */ /* for backwards compatibility */ u32 valid:1; /* actual type if hardware could not support requested timestamp */ u32 actual_type:4; /* accuracy represented in ns units */ u32 accuracy_report:1; /* 0 if accuracy unknown, 1 if accuracy field is valid */ u32 accuracy; /* up to 4.29s, will be packed in separate field */ }; static inline void snd_pcm_pack_audio_tstamp_report(__u32 *data, __u32 *accuracy, const struct snd_pcm_audio_tstamp_report *report) { u32 tmp; tmp = report->accuracy_report; tmp <<= 4; tmp |= report->actual_type; tmp <<= 1; tmp |= report->valid; *data &= 0xffff; /* zero-clear MSBs */ *data |= (tmp << 16); *accuracy = report->accuracy; } struct snd_pcm_runtime { struct snd_pcm_runtime { /* -- Status -- */ /* -- Status -- */ struct snd_pcm_substream *trigger_master; struct snd_pcm_substream *trigger_master; Loading Loading @@ -361,6 +418,11 @@ struct snd_pcm_runtime { struct snd_dma_buffer *dma_buffer_p; /* allocated buffer */ struct snd_dma_buffer *dma_buffer_p; /* allocated buffer */ /* -- audio timestamp config -- */ struct snd_pcm_audio_tstamp_config audio_tstamp_config; struct snd_pcm_audio_tstamp_report audio_tstamp_report; struct timespec driver_tstamp; #if defined(CONFIG_SND_PCM_OSS) || defined(CONFIG_SND_PCM_OSS_MODULE) #if defined(CONFIG_SND_PCM_OSS) || defined(CONFIG_SND_PCM_OSS_MODULE) /* -- OSS things -- */ /* -- OSS things -- */ struct snd_pcm_oss_runtime oss; struct snd_pcm_oss_runtime oss; Loading include/uapi/sound/asound.h +31 −5 Original line number Original line Diff line number Diff line Loading @@ -143,7 +143,7 @@ struct snd_hwdep_dsp_image { * * * * *****************************************************************************/ *****************************************************************************/ #define SNDRV_PCM_VERSION SNDRV_PROTOCOL_VERSION(2, 0, 12) #define SNDRV_PCM_VERSION SNDRV_PROTOCOL_VERSION(2, 0, 13) typedef unsigned long snd_pcm_uframes_t; typedef unsigned long snd_pcm_uframes_t; typedef signed long snd_pcm_sframes_t; typedef signed long snd_pcm_sframes_t; Loading Loading @@ -270,10 +270,17 @@ typedef int __bitwise snd_pcm_subformat_t; #define SNDRV_PCM_INFO_JOINT_DUPLEX 0x00200000 /* playback and capture stream are somewhat correlated */ #define SNDRV_PCM_INFO_JOINT_DUPLEX 0x00200000 /* playback and capture stream are somewhat correlated */ #define SNDRV_PCM_INFO_SYNC_START 0x00400000 /* pcm support some kind of sync go */ #define SNDRV_PCM_INFO_SYNC_START 0x00400000 /* pcm support some kind of sync go */ #define SNDRV_PCM_INFO_NO_PERIOD_WAKEUP 0x00800000 /* period wakeup can be disabled */ #define SNDRV_PCM_INFO_NO_PERIOD_WAKEUP 0x00800000 /* period wakeup can be disabled */ #define SNDRV_PCM_INFO_HAS_WALL_CLOCK 0x01000000 /* has audio wall clock for audio/system time sync */ #define SNDRV_PCM_INFO_HAS_WALL_CLOCK 0x01000000 /* (Deprecated)has audio wall clock for audio/system time sync */ #define SNDRV_PCM_INFO_HAS_LINK_ATIME 0x01000000 /* report hardware link audio time, reset on startup */ #define SNDRV_PCM_INFO_HAS_LINK_ABSOLUTE_ATIME 0x02000000 /* report absolute hardware link audio time, not reset on startup */ #define SNDRV_PCM_INFO_HAS_LINK_ESTIMATED_ATIME 0x04000000 /* report estimated link audio time */ #define SNDRV_PCM_INFO_HAS_LINK_SYNCHRONIZED_ATIME 0x08000000 /* report synchronized audio/system time */ #define SNDRV_PCM_INFO_DRAIN_TRIGGER 0x40000000 /* internal kernel flag - trigger in drain */ #define SNDRV_PCM_INFO_DRAIN_TRIGGER 0x40000000 /* internal kernel flag - trigger in drain */ #define SNDRV_PCM_INFO_FIFO_IN_FRAMES 0x80000000 /* internal kernel flag - FIFO size is in frames */ #define SNDRV_PCM_INFO_FIFO_IN_FRAMES 0x80000000 /* internal kernel flag - FIFO size is in frames */ typedef int __bitwise snd_pcm_state_t; typedef int __bitwise snd_pcm_state_t; #define SNDRV_PCM_STATE_OPEN ((__force snd_pcm_state_t) 0) /* stream is open */ #define SNDRV_PCM_STATE_OPEN ((__force snd_pcm_state_t) 0) /* stream is open */ #define SNDRV_PCM_STATE_SETUP ((__force snd_pcm_state_t) 1) /* stream has a setup */ #define SNDRV_PCM_STATE_SETUP ((__force snd_pcm_state_t) 1) /* stream has a setup */ Loading Loading @@ -411,6 +418,22 @@ struct snd_pcm_channel_info { unsigned int step; /* samples distance in bits */ unsigned int step; /* samples distance in bits */ }; }; enum { /* * first definition for backwards compatibility only, * maps to wallclock/link time for HDAudio playback and DEFAULT/DMA time for everything else */ SNDRV_PCM_AUDIO_TSTAMP_TYPE_COMPAT = 0, /* timestamp definitions */ SNDRV_PCM_AUDIO_TSTAMP_TYPE_DEFAULT = 1, /* DMA time, reported as per hw_ptr */ SNDRV_PCM_AUDIO_TSTAMP_TYPE_LINK = 2, /* link time reported by sample or wallclock counter, reset on startup */ SNDRV_PCM_AUDIO_TSTAMP_TYPE_LINK_ABSOLUTE = 3, /* link time reported by sample or wallclock counter, not reset on startup */ SNDRV_PCM_AUDIO_TSTAMP_TYPE_LINK_ESTIMATED = 4, /* link time estimated indirectly */ SNDRV_PCM_AUDIO_TSTAMP_TYPE_LINK_SYNCHRONIZED = 5, /* link time synchronized with system time */ SNDRV_PCM_AUDIO_TSTAMP_TYPE_LAST = SNDRV_PCM_AUDIO_TSTAMP_TYPE_LINK_SYNCHRONIZED }; struct snd_pcm_status { struct snd_pcm_status { snd_pcm_state_t state; /* stream state */ snd_pcm_state_t state; /* stream state */ struct timespec trigger_tstamp; /* time when stream was started/stopped/paused */ struct timespec trigger_tstamp; /* time when stream was started/stopped/paused */ Loading @@ -422,9 +445,11 @@ struct snd_pcm_status { snd_pcm_uframes_t avail_max; /* max frames available on hw since last status */ snd_pcm_uframes_t avail_max; /* max frames available on hw since last status */ snd_pcm_uframes_t overrange; /* count of ADC (capture) overrange detections from last status */ snd_pcm_uframes_t overrange; /* count of ADC (capture) overrange detections from last status */ snd_pcm_state_t suspended_state; /* suspended stream state */ snd_pcm_state_t suspended_state; /* suspended stream state */ __u32 reserved_alignment; /* must be filled with zero */ __u32 audio_tstamp_data; /* needed for 64-bit alignment, used for configs/report to/from userspace */ struct timespec audio_tstamp; /* from sample counter or wall clock */ struct timespec audio_tstamp; /* sample counter, wall clock, PHC or on-demand sync'ed */ unsigned char reserved[56-sizeof(struct timespec)]; /* must be filled with zero */ struct timespec driver_tstamp; /* useful in case reference system tstamp is reported with delay */ __u32 audio_tstamp_accuracy; /* in ns units, only valid if indicated in audio_tstamp_data */ unsigned char reserved[52-2*sizeof(struct timespec)]; /* must be filled with zero */ }; }; struct snd_pcm_mmap_status { struct snd_pcm_mmap_status { Loading Loading @@ -537,6 +562,7 @@ enum { #define SNDRV_PCM_IOCTL_DELAY _IOR('A', 0x21, snd_pcm_sframes_t) #define SNDRV_PCM_IOCTL_DELAY _IOR('A', 0x21, snd_pcm_sframes_t) #define SNDRV_PCM_IOCTL_HWSYNC _IO('A', 0x22) #define SNDRV_PCM_IOCTL_HWSYNC _IO('A', 0x22) #define SNDRV_PCM_IOCTL_SYNC_PTR _IOWR('A', 0x23, struct snd_pcm_sync_ptr) #define SNDRV_PCM_IOCTL_SYNC_PTR _IOWR('A', 0x23, struct snd_pcm_sync_ptr) #define SNDRV_PCM_IOCTL_STATUS_EXT _IOWR('A', 0x24, struct snd_pcm_status) #define SNDRV_PCM_IOCTL_CHANNEL_INFO _IOR('A', 0x32, struct snd_pcm_channel_info) #define SNDRV_PCM_IOCTL_CHANNEL_INFO _IOR('A', 0x32, struct snd_pcm_channel_info) #define SNDRV_PCM_IOCTL_PREPARE _IO('A', 0x40) #define SNDRV_PCM_IOCTL_PREPARE _IO('A', 0x40) #define SNDRV_PCM_IOCTL_RESET _IO('A', 0x41) #define SNDRV_PCM_IOCTL_RESET _IO('A', 0x41) Loading sound/core/pcm_compat.c +23 −5 Original line number Original line Diff line number Diff line Loading @@ -194,18 +194,30 @@ struct snd_pcm_status32 { u32 avail_max; u32 avail_max; u32 overrange; u32 overrange; s32 suspended_state; s32 suspended_state; u32 reserved_alignment; u32 audio_tstamp_data; struct compat_timespec audio_tstamp; struct compat_timespec audio_tstamp; unsigned char reserved[56-sizeof(struct compat_timespec)]; struct compat_timespec driver_tstamp; u32 audio_tstamp_accuracy; unsigned char reserved[52-2*sizeof(struct compat_timespec)]; } __attribute__((packed)); } __attribute__((packed)); static int snd_pcm_status_user_compat(struct snd_pcm_substream *substream, static int snd_pcm_status_user_compat(struct snd_pcm_substream *substream, struct snd_pcm_status32 __user *src) struct snd_pcm_status32 __user *src, bool ext) { { struct snd_pcm_status status; struct snd_pcm_status status; int err; int err; memset(&status, 0, sizeof(status)); /* * with extension, parameters are read/write, * get audio_tstamp_data from user, * ignore rest of status structure */ if (ext && get_user(status.audio_tstamp_data, (u32 __user *)(&src->audio_tstamp_data))) return -EFAULT; err = snd_pcm_status(substream, &status); err = snd_pcm_status(substream, &status); if (err < 0) if (err < 0) return err; return err; Loading @@ -222,7 +234,10 @@ static int snd_pcm_status_user_compat(struct snd_pcm_substream *substream, put_user(status.avail_max, &src->avail_max) || put_user(status.avail_max, &src->avail_max) || put_user(status.overrange, &src->overrange) || put_user(status.overrange, &src->overrange) || put_user(status.suspended_state, &src->suspended_state) || put_user(status.suspended_state, &src->suspended_state) || compat_put_timespec(&status.audio_tstamp, &src->audio_tstamp)) put_user(status.audio_tstamp_data, &src->audio_tstamp_data) || compat_put_timespec(&status.audio_tstamp, &src->audio_tstamp) || compat_put_timespec(&status.driver_tstamp, &src->driver_tstamp) || put_user(status.audio_tstamp_accuracy, &src->audio_tstamp_accuracy)) return -EFAULT; return -EFAULT; return err; return err; Loading Loading @@ -457,6 +472,7 @@ enum { SNDRV_PCM_IOCTL_HW_PARAMS32 = _IOWR('A', 0x11, struct snd_pcm_hw_params32), SNDRV_PCM_IOCTL_HW_PARAMS32 = _IOWR('A', 0x11, struct snd_pcm_hw_params32), SNDRV_PCM_IOCTL_SW_PARAMS32 = _IOWR('A', 0x13, struct snd_pcm_sw_params32), SNDRV_PCM_IOCTL_SW_PARAMS32 = _IOWR('A', 0x13, struct snd_pcm_sw_params32), SNDRV_PCM_IOCTL_STATUS32 = _IOR('A', 0x20, struct snd_pcm_status32), SNDRV_PCM_IOCTL_STATUS32 = _IOR('A', 0x20, struct snd_pcm_status32), SNDRV_PCM_IOCTL_STATUS_EXT32 = _IOWR('A', 0x24, struct snd_pcm_status32), SNDRV_PCM_IOCTL_DELAY32 = _IOR('A', 0x21, s32), SNDRV_PCM_IOCTL_DELAY32 = _IOR('A', 0x21, s32), SNDRV_PCM_IOCTL_CHANNEL_INFO32 = _IOR('A', 0x32, struct snd_pcm_channel_info32), SNDRV_PCM_IOCTL_CHANNEL_INFO32 = _IOR('A', 0x32, struct snd_pcm_channel_info32), SNDRV_PCM_IOCTL_REWIND32 = _IOW('A', 0x46, u32), SNDRV_PCM_IOCTL_REWIND32 = _IOW('A', 0x46, u32), Loading Loading @@ -517,7 +533,9 @@ static long snd_pcm_ioctl_compat(struct file *file, unsigned int cmd, unsigned l case SNDRV_PCM_IOCTL_SW_PARAMS32: case SNDRV_PCM_IOCTL_SW_PARAMS32: return snd_pcm_ioctl_sw_params_compat(substream, argp); return snd_pcm_ioctl_sw_params_compat(substream, argp); case SNDRV_PCM_IOCTL_STATUS32: case SNDRV_PCM_IOCTL_STATUS32: return snd_pcm_status_user_compat(substream, argp); return snd_pcm_status_user_compat(substream, argp, false); case SNDRV_PCM_IOCTL_STATUS_EXT32: return snd_pcm_status_user_compat(substream, argp, true); case SNDRV_PCM_IOCTL_SYNC_PTR32: case SNDRV_PCM_IOCTL_SYNC_PTR32: return snd_pcm_ioctl_sync_ptr_compat(substream, argp); return snd_pcm_ioctl_sync_ptr_compat(substream, argp); case SNDRV_PCM_IOCTL_CHANNEL_INFO32: case SNDRV_PCM_IOCTL_CHANNEL_INFO32: Loading sound/core/pcm_lib.c +59 −29 Original line number Original line Diff line number Diff line Loading @@ -232,6 +232,49 @@ int snd_pcm_update_state(struct snd_pcm_substream *substream, return 0; return 0; } } static void update_audio_tstamp(struct snd_pcm_substream *substream, struct timespec *curr_tstamp, struct timespec *audio_tstamp) { struct snd_pcm_runtime *runtime = substream->runtime; u64 audio_frames, audio_nsecs; struct timespec driver_tstamp; if (runtime->tstamp_mode != SNDRV_PCM_TSTAMP_ENABLE) return; if (!(substream->ops->get_time_info) || (runtime->audio_tstamp_report.actual_type == SNDRV_PCM_AUDIO_TSTAMP_TYPE_DEFAULT)) { /* * provide audio timestamp derived from pointer position * add delay only if requested */ audio_frames = runtime->hw_ptr_wrap + runtime->status->hw_ptr; if (runtime->audio_tstamp_config.report_delay) { if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) audio_frames -= runtime->delay; else audio_frames += runtime->delay; } audio_nsecs = div_u64(audio_frames * 1000000000LL, runtime->rate); *audio_tstamp = ns_to_timespec(audio_nsecs); } runtime->status->audio_tstamp = *audio_tstamp; runtime->status->tstamp = *curr_tstamp; /* * re-take a driver timestamp to let apps detect if the reference tstamp * read by low-level hardware was provided with a delay */ snd_pcm_gettime(substream->runtime, (struct timespec *)&driver_tstamp); runtime->driver_tstamp = driver_tstamp; } static int snd_pcm_update_hw_ptr0(struct snd_pcm_substream *substream, static int snd_pcm_update_hw_ptr0(struct snd_pcm_substream *substream, unsigned int in_interrupt) unsigned int in_interrupt) { { Loading @@ -256,11 +299,18 @@ static int snd_pcm_update_hw_ptr0(struct snd_pcm_substream *substream, pos = substream->ops->pointer(substream); pos = substream->ops->pointer(substream); curr_jiffies = jiffies; curr_jiffies = jiffies; if (runtime->tstamp_mode == SNDRV_PCM_TSTAMP_ENABLE) { if (runtime->tstamp_mode == SNDRV_PCM_TSTAMP_ENABLE) { if ((substream->ops->get_time_info) && (runtime->audio_tstamp_config.type_requested != SNDRV_PCM_AUDIO_TSTAMP_TYPE_DEFAULT)) { substream->ops->get_time_info(substream, &curr_tstamp, &audio_tstamp, &runtime->audio_tstamp_config, &runtime->audio_tstamp_report); /* re-test in case tstamp type is not supported in hardware and was demoted to DEFAULT */ if (runtime->audio_tstamp_report.actual_type == SNDRV_PCM_AUDIO_TSTAMP_TYPE_DEFAULT) snd_pcm_gettime(runtime, (struct timespec *)&curr_tstamp); } else snd_pcm_gettime(runtime, (struct timespec *)&curr_tstamp); snd_pcm_gettime(runtime, (struct timespec *)&curr_tstamp); if ((runtime->hw.info & SNDRV_PCM_INFO_HAS_WALL_CLOCK) && (substream->ops->wall_clock)) substream->ops->wall_clock(substream, &audio_tstamp); } } if (pos == SNDRV_PCM_POS_XRUN) { if (pos == SNDRV_PCM_POS_XRUN) { Loading Loading @@ -403,8 +453,10 @@ static int snd_pcm_update_hw_ptr0(struct snd_pcm_substream *substream, } } no_delta_check: no_delta_check: if (runtime->status->hw_ptr == new_hw_ptr) if (runtime->status->hw_ptr == new_hw_ptr) { update_audio_tstamp(substream, &curr_tstamp, &audio_tstamp); return 0; return 0; } if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK && if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK && runtime->silence_size > 0) runtime->silence_size > 0) Loading @@ -426,30 +478,8 @@ static int snd_pcm_update_hw_ptr0(struct snd_pcm_substream *substream, snd_BUG_ON(crossed_boundary != 1); snd_BUG_ON(crossed_boundary != 1); runtime->hw_ptr_wrap += runtime->boundary; runtime->hw_ptr_wrap += runtime->boundary; } } if (runtime->tstamp_mode == SNDRV_PCM_TSTAMP_ENABLE) { runtime->status->tstamp = curr_tstamp; if (!(runtime->hw.info & SNDRV_PCM_INFO_HAS_WALL_CLOCK)) { /* * no wall clock available, provide audio timestamp * derived from pointer position+delay */ u64 audio_frames, audio_nsecs; if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) update_audio_tstamp(substream, &curr_tstamp, &audio_tstamp); audio_frames = runtime->hw_ptr_wrap + runtime->status->hw_ptr - runtime->delay; else audio_frames = runtime->hw_ptr_wrap + runtime->status->hw_ptr + runtime->delay; audio_nsecs = div_u64(audio_frames * 1000000000LL, runtime->rate); audio_tstamp = ns_to_timespec(audio_nsecs); } runtime->status->audio_tstamp = audio_tstamp; } return snd_pcm_update_state(substream, runtime); return snd_pcm_update_state(substream, runtime); } } Loading Loading
Documentation/sound/alsa/timestamping.txt 0 → 100644 +200 −0 Original line number Original line Diff line number Diff line The ALSA API can provide two different system timestamps: - Trigger_tstamp is the system time snapshot taken when the .trigger callback is invoked. This snapshot is taken by the ALSA core in the general case, but specific hardware may have synchronization capabilities or conversely may only be able to provide a correct estimate with a delay. In the latter two cases, the low-level driver is responsible for updating the trigger_tstamp at the most appropriate and precise moment. Applications should not rely solely on the first trigger_tstamp but update their internal calculations if the driver provides a refined estimate with a delay. - tstamp is the current system timestamp updated during the last event or application query. The difference (tstamp - trigger_tstamp) defines the elapsed time. The ALSA API provides reports two basic pieces of information, avail and delay, which combined with the trigger and current system timestamps allow for applications to keep track of the 'fullness' of the ring buffer and the amount of queued samples. The use of these different pointers and time information depends on the application needs: - 'avail' reports how much can be written in the ring buffer - 'delay' reports the time it will take to hear a new sample after all queued samples have been played out. When timestamps are enabled, the avail/delay information is reported along with a snapshot of system time. Applications can select from CLOCK_REALTIME (NTP corrections including going backwards), CLOCK_MONOTONIC (NTP corrections but never going backwards), CLOCK_MONOTIC_RAW (without NTP corrections) and change the mode dynamically with sw_params The ALSA API also provide an audio_tstamp which reflects the passage of time as measured by different components of audio hardware. In ascii-art, this could be represented as follows (for the playback case): --------------------------------------------------------------> time ^ ^ ^ ^ ^ | | | | | analog link dma app FullBuffer time time time time time | | | | | |< codec delay >|<--hw delay-->|<queued samples>|<---avail->| |<----------------- delay---------------------->| | |<----ring buffer length---->| The analog time is taken at the last stage of the playback, as close as possible to the actual transducer The link time is taken at the output of the SOC/chipset as the samples are pushed on a link. The link time can be directly measured if supported in hardware by sample counters or wallclocks (e.g. with HDAudio 24MHz or PTP clock for networked solutions) or indirectly estimated (e.g. with the frame counter in USB). The DMA time is measured using counters - typically the least reliable of all measurements due to the bursty natured of DMA transfers. The app time corresponds to the time tracked by an application after writing in the ring buffer. The application can query what the hardware supports, define which audio time it wants reported by selecting the relevant settings in audio_tstamp_config fields, get an estimate of the timestamp accuracy. It can also request the delay-to-analog be included in the measurement. Direct access to the link time is very interesting on platforms that provide an embedded DSP; measuring directly the link time with dedicated hardware, possibly synchronized with system time, removes the need to keep track of internal DSP processing times and latency. In case the application requests an audio tstamp that is not supported in hardware/low-level driver, the type is overridden as DEFAULT and the timestamp will report the DMA time based on the hw_pointer value. For backwards compatibility with previous implementations that did not provide timestamp selection, with a zero-valued COMPAT timestamp type the results will default to the HDAudio wall clock for playback streams and to the DMA time (hw_ptr) in all other cases. The audio timestamp accuracy can be returned to user-space, so that appropriate decisions are made: - for dma time (default), the granularity of the transfers can be inferred from the steps between updates and in turn provide information on how much the application pointer can be rewound safely. - the link time can be used to track long-term drifts between audio and system time using the (tstamp-trigger_tstamp)/audio_tstamp ratio, the precision helps define how much smoothing/low-pass filtering is required. The link time can be either reset on startup or reported as is (the latter being useful to compare progress of different streams - but may require the wallclock to be always running and not wrap-around during idle periods). If supported in hardware, the absolute link time could also be used to define a precise start time (patches WIP) - including the delay in the audio timestamp may counter-intuitively not increase the precision of timestamps, e.g. if a codec includes variable-latency DSP processing or a chain of hardware components the delay is typically not known with precision. The accuracy is reported in nanosecond units (using an unsigned 32-bit word), which gives a max precision of 4.29s, more than enough for audio applications... Due to the varied nature of timestamping needs, even for a single application, the audio_tstamp_config can be changed dynamically. In the STATUS ioctl, the parameters are read-only and do not allow for any application selection. To work around this limitation without impacting legacy applications, a new STATUS_EXT ioctl is introduced with read/write parameters. ALSA-lib will be modified to make use of STATUS_EXT and effectively deprecate STATUS. The ALSA API only allows for a single audio timestamp to be reported at a time. This is a conscious design decision, reading the audio timestamps from hardware registers or from IPC takes time, the more timestamps are read the more imprecise the combined measurements are. To avoid any interpretation issues, a single (system, audio) timestamp is reported. Applications that need different timestamps will be required to issue multiple queries and perform an interpolation of the results In some hardware-specific configuration, the system timestamp is latched by a low-level audio subsytem, and the information provided back to the driver. Due to potential delays in the communication with the hardware, there is a risk of misalignment with the avail and delay information. To make sure applications are not confused, a driver_timestamp field is added in the snd_pcm_status structure; this timestamp shows when the information is put together by the driver before returning from the STATUS and STATUS_EXT ioctl. in most cases this driver_timestamp will be identical to the regular system tstamp. Examples of typestamping with HDaudio: 1. DMA timestamp, no compensation for DMA+analog delay $ ./audio_time -p --ts_type=1 playback: systime: 341121338 nsec, audio time 342000000 nsec, systime delta -878662 playback: systime: 426236663 nsec, audio time 427187500 nsec, systime delta -950837 playback: systime: 597080580 nsec, audio time 598000000 nsec, systime delta -919420 playback: systime: 682059782 nsec, audio time 683020833 nsec, systime delta -961051 playback: systime: 852896415 nsec, audio time 853854166 nsec, systime delta -957751 playback: systime: 937903344 nsec, audio time 938854166 nsec, systime delta -950822 2. DMA timestamp, compensation for DMA+analog delay $ ./audio_time -p --ts_type=1 -d playback: systime: 341053347 nsec, audio time 341062500 nsec, systime delta -9153 playback: systime: 426072447 nsec, audio time 426062500 nsec, systime delta 9947 playback: systime: 596899518 nsec, audio time 596895833 nsec, systime delta 3685 playback: systime: 681915317 nsec, audio time 681916666 nsec, systime delta -1349 playback: systime: 852741306 nsec, audio time 852750000 nsec, systime delta -8694 3. link timestamp, compensation for DMA+analog delay $ ./audio_time -p --ts_type=2 -d playback: systime: 341060004 nsec, audio time 341062791 nsec, systime delta -2787 playback: systime: 426242074 nsec, audio time 426244875 nsec, systime delta -2801 playback: systime: 597080992 nsec, audio time 597084583 nsec, systime delta -3591 playback: systime: 682084512 nsec, audio time 682088291 nsec, systime delta -3779 playback: systime: 852936229 nsec, audio time 852940916 nsec, systime delta -4687 playback: systime: 938107562 nsec, audio time 938112708 nsec, systime delta -5146 Example 1 shows that the timestamp at the DMA level is close to 1ms ahead of the actual playback time (as a side time this sort of measurement can help define rewind safeguards). Compensating for the DMA-link delay in example 2 helps remove the hardware buffering abut the information is still very jittery, with up to one sample of error. In example 3 where the timestamps are measured with the link wallclock, the timestamps show a monotonic behavior and a lower dispersion. Example 3 and 4 are with USB audio class. Example 3 shows a high offset between audio time and system time due to buffering. Example 4 shows how compensating for the delay exposes a 1ms accuracy (due to the use of the frame counter by the driver) Example 3: DMA timestamp, no compensation for delay, delta of ~5ms $ ./audio_time -p -Dhw:1 -t1 playback: systime: 120174019 nsec, audio time 125000000 nsec, systime delta -4825981 playback: systime: 245041136 nsec, audio time 250000000 nsec, systime delta -4958864 playback: systime: 370106088 nsec, audio time 375000000 nsec, systime delta -4893912 playback: systime: 495040065 nsec, audio time 500000000 nsec, systime delta -4959935 playback: systime: 620038179 nsec, audio time 625000000 nsec, systime delta -4961821 playback: systime: 745087741 nsec, audio time 750000000 nsec, systime delta -4912259 playback: systime: 870037336 nsec, audio time 875000000 nsec, systime delta -4962664 Example 4: DMA timestamp, compensation for delay, delay of ~1ms $ ./audio_time -p -Dhw:1 -t1 -d playback: systime: 120190520 nsec, audio time 120000000 nsec, systime delta 190520 playback: systime: 245036740 nsec, audio time 244000000 nsec, systime delta 1036740 playback: systime: 370034081 nsec, audio time 369000000 nsec, systime delta 1034081 playback: systime: 495159907 nsec, audio time 494000000 nsec, systime delta 1159907 playback: systime: 620098824 nsec, audio time 619000000 nsec, systime delta 1098824 playback: systime: 745031847 nsec, audio time 744000000 nsec, systime delta 1031847
include/sound/pcm.h +64 −2 Original line number Original line Diff line number Diff line Loading @@ -60,6 +60,9 @@ struct snd_pcm_hardware { struct snd_pcm_substream; struct snd_pcm_substream; struct snd_pcm_audio_tstamp_config; /* definitions further down */ struct snd_pcm_audio_tstamp_report; struct snd_pcm_ops { struct snd_pcm_ops { int (*open)(struct snd_pcm_substream *substream); int (*open)(struct snd_pcm_substream *substream); int (*close)(struct snd_pcm_substream *substream); int (*close)(struct snd_pcm_substream *substream); Loading @@ -71,8 +74,10 @@ struct snd_pcm_ops { int (*prepare)(struct snd_pcm_substream *substream); int (*prepare)(struct snd_pcm_substream *substream); int (*trigger)(struct snd_pcm_substream *substream, int cmd); int (*trigger)(struct snd_pcm_substream *substream, int cmd); snd_pcm_uframes_t (*pointer)(struct snd_pcm_substream *substream); snd_pcm_uframes_t (*pointer)(struct snd_pcm_substream *substream); int (*wall_clock)(struct snd_pcm_substream *substream, int (*get_time_info)(struct snd_pcm_substream *substream, struct timespec *audio_ts); struct timespec *system_ts, struct timespec *audio_ts, struct snd_pcm_audio_tstamp_config *audio_tstamp_config, struct snd_pcm_audio_tstamp_report *audio_tstamp_report); int (*copy)(struct snd_pcm_substream *substream, int channel, int (*copy)(struct snd_pcm_substream *substream, int channel, snd_pcm_uframes_t pos, snd_pcm_uframes_t pos, void __user *buf, snd_pcm_uframes_t count); void __user *buf, snd_pcm_uframes_t count); Loading Loading @@ -281,6 +286,58 @@ struct snd_pcm_hw_constraint_ranges { struct snd_pcm_hwptr_log; struct snd_pcm_hwptr_log; /* * userspace-provided audio timestamp config to kernel, * structure is for internal use only and filled with dedicated unpack routine */ struct snd_pcm_audio_tstamp_config { /* 5 of max 16 bits used */ u32 type_requested:4; u32 report_delay:1; /* add total delay to A/D or D/A */ }; static inline void snd_pcm_unpack_audio_tstamp_config(__u32 data, struct snd_pcm_audio_tstamp_config *config) { config->type_requested = data & 0xF; config->report_delay = (data >> 4) & 1; } /* * kernel-provided audio timestamp report to user-space * structure is for internal use only and read by dedicated pack routine */ struct snd_pcm_audio_tstamp_report { /* 6 of max 16 bits used for bit-fields */ /* for backwards compatibility */ u32 valid:1; /* actual type if hardware could not support requested timestamp */ u32 actual_type:4; /* accuracy represented in ns units */ u32 accuracy_report:1; /* 0 if accuracy unknown, 1 if accuracy field is valid */ u32 accuracy; /* up to 4.29s, will be packed in separate field */ }; static inline void snd_pcm_pack_audio_tstamp_report(__u32 *data, __u32 *accuracy, const struct snd_pcm_audio_tstamp_report *report) { u32 tmp; tmp = report->accuracy_report; tmp <<= 4; tmp |= report->actual_type; tmp <<= 1; tmp |= report->valid; *data &= 0xffff; /* zero-clear MSBs */ *data |= (tmp << 16); *accuracy = report->accuracy; } struct snd_pcm_runtime { struct snd_pcm_runtime { /* -- Status -- */ /* -- Status -- */ struct snd_pcm_substream *trigger_master; struct snd_pcm_substream *trigger_master; Loading Loading @@ -361,6 +418,11 @@ struct snd_pcm_runtime { struct snd_dma_buffer *dma_buffer_p; /* allocated buffer */ struct snd_dma_buffer *dma_buffer_p; /* allocated buffer */ /* -- audio timestamp config -- */ struct snd_pcm_audio_tstamp_config audio_tstamp_config; struct snd_pcm_audio_tstamp_report audio_tstamp_report; struct timespec driver_tstamp; #if defined(CONFIG_SND_PCM_OSS) || defined(CONFIG_SND_PCM_OSS_MODULE) #if defined(CONFIG_SND_PCM_OSS) || defined(CONFIG_SND_PCM_OSS_MODULE) /* -- OSS things -- */ /* -- OSS things -- */ struct snd_pcm_oss_runtime oss; struct snd_pcm_oss_runtime oss; Loading
include/uapi/sound/asound.h +31 −5 Original line number Original line Diff line number Diff line Loading @@ -143,7 +143,7 @@ struct snd_hwdep_dsp_image { * * * * *****************************************************************************/ *****************************************************************************/ #define SNDRV_PCM_VERSION SNDRV_PROTOCOL_VERSION(2, 0, 12) #define SNDRV_PCM_VERSION SNDRV_PROTOCOL_VERSION(2, 0, 13) typedef unsigned long snd_pcm_uframes_t; typedef unsigned long snd_pcm_uframes_t; typedef signed long snd_pcm_sframes_t; typedef signed long snd_pcm_sframes_t; Loading Loading @@ -270,10 +270,17 @@ typedef int __bitwise snd_pcm_subformat_t; #define SNDRV_PCM_INFO_JOINT_DUPLEX 0x00200000 /* playback and capture stream are somewhat correlated */ #define SNDRV_PCM_INFO_JOINT_DUPLEX 0x00200000 /* playback and capture stream are somewhat correlated */ #define SNDRV_PCM_INFO_SYNC_START 0x00400000 /* pcm support some kind of sync go */ #define SNDRV_PCM_INFO_SYNC_START 0x00400000 /* pcm support some kind of sync go */ #define SNDRV_PCM_INFO_NO_PERIOD_WAKEUP 0x00800000 /* period wakeup can be disabled */ #define SNDRV_PCM_INFO_NO_PERIOD_WAKEUP 0x00800000 /* period wakeup can be disabled */ #define SNDRV_PCM_INFO_HAS_WALL_CLOCK 0x01000000 /* has audio wall clock for audio/system time sync */ #define SNDRV_PCM_INFO_HAS_WALL_CLOCK 0x01000000 /* (Deprecated)has audio wall clock for audio/system time sync */ #define SNDRV_PCM_INFO_HAS_LINK_ATIME 0x01000000 /* report hardware link audio time, reset on startup */ #define SNDRV_PCM_INFO_HAS_LINK_ABSOLUTE_ATIME 0x02000000 /* report absolute hardware link audio time, not reset on startup */ #define SNDRV_PCM_INFO_HAS_LINK_ESTIMATED_ATIME 0x04000000 /* report estimated link audio time */ #define SNDRV_PCM_INFO_HAS_LINK_SYNCHRONIZED_ATIME 0x08000000 /* report synchronized audio/system time */ #define SNDRV_PCM_INFO_DRAIN_TRIGGER 0x40000000 /* internal kernel flag - trigger in drain */ #define SNDRV_PCM_INFO_DRAIN_TRIGGER 0x40000000 /* internal kernel flag - trigger in drain */ #define SNDRV_PCM_INFO_FIFO_IN_FRAMES 0x80000000 /* internal kernel flag - FIFO size is in frames */ #define SNDRV_PCM_INFO_FIFO_IN_FRAMES 0x80000000 /* internal kernel flag - FIFO size is in frames */ typedef int __bitwise snd_pcm_state_t; typedef int __bitwise snd_pcm_state_t; #define SNDRV_PCM_STATE_OPEN ((__force snd_pcm_state_t) 0) /* stream is open */ #define SNDRV_PCM_STATE_OPEN ((__force snd_pcm_state_t) 0) /* stream is open */ #define SNDRV_PCM_STATE_SETUP ((__force snd_pcm_state_t) 1) /* stream has a setup */ #define SNDRV_PCM_STATE_SETUP ((__force snd_pcm_state_t) 1) /* stream has a setup */ Loading Loading @@ -411,6 +418,22 @@ struct snd_pcm_channel_info { unsigned int step; /* samples distance in bits */ unsigned int step; /* samples distance in bits */ }; }; enum { /* * first definition for backwards compatibility only, * maps to wallclock/link time for HDAudio playback and DEFAULT/DMA time for everything else */ SNDRV_PCM_AUDIO_TSTAMP_TYPE_COMPAT = 0, /* timestamp definitions */ SNDRV_PCM_AUDIO_TSTAMP_TYPE_DEFAULT = 1, /* DMA time, reported as per hw_ptr */ SNDRV_PCM_AUDIO_TSTAMP_TYPE_LINK = 2, /* link time reported by sample or wallclock counter, reset on startup */ SNDRV_PCM_AUDIO_TSTAMP_TYPE_LINK_ABSOLUTE = 3, /* link time reported by sample or wallclock counter, not reset on startup */ SNDRV_PCM_AUDIO_TSTAMP_TYPE_LINK_ESTIMATED = 4, /* link time estimated indirectly */ SNDRV_PCM_AUDIO_TSTAMP_TYPE_LINK_SYNCHRONIZED = 5, /* link time synchronized with system time */ SNDRV_PCM_AUDIO_TSTAMP_TYPE_LAST = SNDRV_PCM_AUDIO_TSTAMP_TYPE_LINK_SYNCHRONIZED }; struct snd_pcm_status { struct snd_pcm_status { snd_pcm_state_t state; /* stream state */ snd_pcm_state_t state; /* stream state */ struct timespec trigger_tstamp; /* time when stream was started/stopped/paused */ struct timespec trigger_tstamp; /* time when stream was started/stopped/paused */ Loading @@ -422,9 +445,11 @@ struct snd_pcm_status { snd_pcm_uframes_t avail_max; /* max frames available on hw since last status */ snd_pcm_uframes_t avail_max; /* max frames available on hw since last status */ snd_pcm_uframes_t overrange; /* count of ADC (capture) overrange detections from last status */ snd_pcm_uframes_t overrange; /* count of ADC (capture) overrange detections from last status */ snd_pcm_state_t suspended_state; /* suspended stream state */ snd_pcm_state_t suspended_state; /* suspended stream state */ __u32 reserved_alignment; /* must be filled with zero */ __u32 audio_tstamp_data; /* needed for 64-bit alignment, used for configs/report to/from userspace */ struct timespec audio_tstamp; /* from sample counter or wall clock */ struct timespec audio_tstamp; /* sample counter, wall clock, PHC or on-demand sync'ed */ unsigned char reserved[56-sizeof(struct timespec)]; /* must be filled with zero */ struct timespec driver_tstamp; /* useful in case reference system tstamp is reported with delay */ __u32 audio_tstamp_accuracy; /* in ns units, only valid if indicated in audio_tstamp_data */ unsigned char reserved[52-2*sizeof(struct timespec)]; /* must be filled with zero */ }; }; struct snd_pcm_mmap_status { struct snd_pcm_mmap_status { Loading Loading @@ -537,6 +562,7 @@ enum { #define SNDRV_PCM_IOCTL_DELAY _IOR('A', 0x21, snd_pcm_sframes_t) #define SNDRV_PCM_IOCTL_DELAY _IOR('A', 0x21, snd_pcm_sframes_t) #define SNDRV_PCM_IOCTL_HWSYNC _IO('A', 0x22) #define SNDRV_PCM_IOCTL_HWSYNC _IO('A', 0x22) #define SNDRV_PCM_IOCTL_SYNC_PTR _IOWR('A', 0x23, struct snd_pcm_sync_ptr) #define SNDRV_PCM_IOCTL_SYNC_PTR _IOWR('A', 0x23, struct snd_pcm_sync_ptr) #define SNDRV_PCM_IOCTL_STATUS_EXT _IOWR('A', 0x24, struct snd_pcm_status) #define SNDRV_PCM_IOCTL_CHANNEL_INFO _IOR('A', 0x32, struct snd_pcm_channel_info) #define SNDRV_PCM_IOCTL_CHANNEL_INFO _IOR('A', 0x32, struct snd_pcm_channel_info) #define SNDRV_PCM_IOCTL_PREPARE _IO('A', 0x40) #define SNDRV_PCM_IOCTL_PREPARE _IO('A', 0x40) #define SNDRV_PCM_IOCTL_RESET _IO('A', 0x41) #define SNDRV_PCM_IOCTL_RESET _IO('A', 0x41) Loading
sound/core/pcm_compat.c +23 −5 Original line number Original line Diff line number Diff line Loading @@ -194,18 +194,30 @@ struct snd_pcm_status32 { u32 avail_max; u32 avail_max; u32 overrange; u32 overrange; s32 suspended_state; s32 suspended_state; u32 reserved_alignment; u32 audio_tstamp_data; struct compat_timespec audio_tstamp; struct compat_timespec audio_tstamp; unsigned char reserved[56-sizeof(struct compat_timespec)]; struct compat_timespec driver_tstamp; u32 audio_tstamp_accuracy; unsigned char reserved[52-2*sizeof(struct compat_timespec)]; } __attribute__((packed)); } __attribute__((packed)); static int snd_pcm_status_user_compat(struct snd_pcm_substream *substream, static int snd_pcm_status_user_compat(struct snd_pcm_substream *substream, struct snd_pcm_status32 __user *src) struct snd_pcm_status32 __user *src, bool ext) { { struct snd_pcm_status status; struct snd_pcm_status status; int err; int err; memset(&status, 0, sizeof(status)); /* * with extension, parameters are read/write, * get audio_tstamp_data from user, * ignore rest of status structure */ if (ext && get_user(status.audio_tstamp_data, (u32 __user *)(&src->audio_tstamp_data))) return -EFAULT; err = snd_pcm_status(substream, &status); err = snd_pcm_status(substream, &status); if (err < 0) if (err < 0) return err; return err; Loading @@ -222,7 +234,10 @@ static int snd_pcm_status_user_compat(struct snd_pcm_substream *substream, put_user(status.avail_max, &src->avail_max) || put_user(status.avail_max, &src->avail_max) || put_user(status.overrange, &src->overrange) || put_user(status.overrange, &src->overrange) || put_user(status.suspended_state, &src->suspended_state) || put_user(status.suspended_state, &src->suspended_state) || compat_put_timespec(&status.audio_tstamp, &src->audio_tstamp)) put_user(status.audio_tstamp_data, &src->audio_tstamp_data) || compat_put_timespec(&status.audio_tstamp, &src->audio_tstamp) || compat_put_timespec(&status.driver_tstamp, &src->driver_tstamp) || put_user(status.audio_tstamp_accuracy, &src->audio_tstamp_accuracy)) return -EFAULT; return -EFAULT; return err; return err; Loading Loading @@ -457,6 +472,7 @@ enum { SNDRV_PCM_IOCTL_HW_PARAMS32 = _IOWR('A', 0x11, struct snd_pcm_hw_params32), SNDRV_PCM_IOCTL_HW_PARAMS32 = _IOWR('A', 0x11, struct snd_pcm_hw_params32), SNDRV_PCM_IOCTL_SW_PARAMS32 = _IOWR('A', 0x13, struct snd_pcm_sw_params32), SNDRV_PCM_IOCTL_SW_PARAMS32 = _IOWR('A', 0x13, struct snd_pcm_sw_params32), SNDRV_PCM_IOCTL_STATUS32 = _IOR('A', 0x20, struct snd_pcm_status32), SNDRV_PCM_IOCTL_STATUS32 = _IOR('A', 0x20, struct snd_pcm_status32), SNDRV_PCM_IOCTL_STATUS_EXT32 = _IOWR('A', 0x24, struct snd_pcm_status32), SNDRV_PCM_IOCTL_DELAY32 = _IOR('A', 0x21, s32), SNDRV_PCM_IOCTL_DELAY32 = _IOR('A', 0x21, s32), SNDRV_PCM_IOCTL_CHANNEL_INFO32 = _IOR('A', 0x32, struct snd_pcm_channel_info32), SNDRV_PCM_IOCTL_CHANNEL_INFO32 = _IOR('A', 0x32, struct snd_pcm_channel_info32), SNDRV_PCM_IOCTL_REWIND32 = _IOW('A', 0x46, u32), SNDRV_PCM_IOCTL_REWIND32 = _IOW('A', 0x46, u32), Loading Loading @@ -517,7 +533,9 @@ static long snd_pcm_ioctl_compat(struct file *file, unsigned int cmd, unsigned l case SNDRV_PCM_IOCTL_SW_PARAMS32: case SNDRV_PCM_IOCTL_SW_PARAMS32: return snd_pcm_ioctl_sw_params_compat(substream, argp); return snd_pcm_ioctl_sw_params_compat(substream, argp); case SNDRV_PCM_IOCTL_STATUS32: case SNDRV_PCM_IOCTL_STATUS32: return snd_pcm_status_user_compat(substream, argp); return snd_pcm_status_user_compat(substream, argp, false); case SNDRV_PCM_IOCTL_STATUS_EXT32: return snd_pcm_status_user_compat(substream, argp, true); case SNDRV_PCM_IOCTL_SYNC_PTR32: case SNDRV_PCM_IOCTL_SYNC_PTR32: return snd_pcm_ioctl_sync_ptr_compat(substream, argp); return snd_pcm_ioctl_sync_ptr_compat(substream, argp); case SNDRV_PCM_IOCTL_CHANNEL_INFO32: case SNDRV_PCM_IOCTL_CHANNEL_INFO32: Loading
sound/core/pcm_lib.c +59 −29 Original line number Original line Diff line number Diff line Loading @@ -232,6 +232,49 @@ int snd_pcm_update_state(struct snd_pcm_substream *substream, return 0; return 0; } } static void update_audio_tstamp(struct snd_pcm_substream *substream, struct timespec *curr_tstamp, struct timespec *audio_tstamp) { struct snd_pcm_runtime *runtime = substream->runtime; u64 audio_frames, audio_nsecs; struct timespec driver_tstamp; if (runtime->tstamp_mode != SNDRV_PCM_TSTAMP_ENABLE) return; if (!(substream->ops->get_time_info) || (runtime->audio_tstamp_report.actual_type == SNDRV_PCM_AUDIO_TSTAMP_TYPE_DEFAULT)) { /* * provide audio timestamp derived from pointer position * add delay only if requested */ audio_frames = runtime->hw_ptr_wrap + runtime->status->hw_ptr; if (runtime->audio_tstamp_config.report_delay) { if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) audio_frames -= runtime->delay; else audio_frames += runtime->delay; } audio_nsecs = div_u64(audio_frames * 1000000000LL, runtime->rate); *audio_tstamp = ns_to_timespec(audio_nsecs); } runtime->status->audio_tstamp = *audio_tstamp; runtime->status->tstamp = *curr_tstamp; /* * re-take a driver timestamp to let apps detect if the reference tstamp * read by low-level hardware was provided with a delay */ snd_pcm_gettime(substream->runtime, (struct timespec *)&driver_tstamp); runtime->driver_tstamp = driver_tstamp; } static int snd_pcm_update_hw_ptr0(struct snd_pcm_substream *substream, static int snd_pcm_update_hw_ptr0(struct snd_pcm_substream *substream, unsigned int in_interrupt) unsigned int in_interrupt) { { Loading @@ -256,11 +299,18 @@ static int snd_pcm_update_hw_ptr0(struct snd_pcm_substream *substream, pos = substream->ops->pointer(substream); pos = substream->ops->pointer(substream); curr_jiffies = jiffies; curr_jiffies = jiffies; if (runtime->tstamp_mode == SNDRV_PCM_TSTAMP_ENABLE) { if (runtime->tstamp_mode == SNDRV_PCM_TSTAMP_ENABLE) { if ((substream->ops->get_time_info) && (runtime->audio_tstamp_config.type_requested != SNDRV_PCM_AUDIO_TSTAMP_TYPE_DEFAULT)) { substream->ops->get_time_info(substream, &curr_tstamp, &audio_tstamp, &runtime->audio_tstamp_config, &runtime->audio_tstamp_report); /* re-test in case tstamp type is not supported in hardware and was demoted to DEFAULT */ if (runtime->audio_tstamp_report.actual_type == SNDRV_PCM_AUDIO_TSTAMP_TYPE_DEFAULT) snd_pcm_gettime(runtime, (struct timespec *)&curr_tstamp); } else snd_pcm_gettime(runtime, (struct timespec *)&curr_tstamp); snd_pcm_gettime(runtime, (struct timespec *)&curr_tstamp); if ((runtime->hw.info & SNDRV_PCM_INFO_HAS_WALL_CLOCK) && (substream->ops->wall_clock)) substream->ops->wall_clock(substream, &audio_tstamp); } } if (pos == SNDRV_PCM_POS_XRUN) { if (pos == SNDRV_PCM_POS_XRUN) { Loading Loading @@ -403,8 +453,10 @@ static int snd_pcm_update_hw_ptr0(struct snd_pcm_substream *substream, } } no_delta_check: no_delta_check: if (runtime->status->hw_ptr == new_hw_ptr) if (runtime->status->hw_ptr == new_hw_ptr) { update_audio_tstamp(substream, &curr_tstamp, &audio_tstamp); return 0; return 0; } if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK && if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK && runtime->silence_size > 0) runtime->silence_size > 0) Loading @@ -426,30 +478,8 @@ static int snd_pcm_update_hw_ptr0(struct snd_pcm_substream *substream, snd_BUG_ON(crossed_boundary != 1); snd_BUG_ON(crossed_boundary != 1); runtime->hw_ptr_wrap += runtime->boundary; runtime->hw_ptr_wrap += runtime->boundary; } } if (runtime->tstamp_mode == SNDRV_PCM_TSTAMP_ENABLE) { runtime->status->tstamp = curr_tstamp; if (!(runtime->hw.info & SNDRV_PCM_INFO_HAS_WALL_CLOCK)) { /* * no wall clock available, provide audio timestamp * derived from pointer position+delay */ u64 audio_frames, audio_nsecs; if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) update_audio_tstamp(substream, &curr_tstamp, &audio_tstamp); audio_frames = runtime->hw_ptr_wrap + runtime->status->hw_ptr - runtime->delay; else audio_frames = runtime->hw_ptr_wrap + runtime->status->hw_ptr + runtime->delay; audio_nsecs = div_u64(audio_frames * 1000000000LL, runtime->rate); audio_tstamp = ns_to_timespec(audio_nsecs); } runtime->status->audio_tstamp = audio_tstamp; } return snd_pcm_update_state(substream, runtime); return snd_pcm_update_state(substream, runtime); } } Loading
