Commit e4f34cf6 authored Jan 05, 2017 by Takashi Sakamoto Committed by Takashi Iwai Jan 05, 2017

Revert "ALSA: firewire-lib: change structure member with proper type"



This reverts commit 6b7e95d1. This commit
is based on a concern about value of the given parameter. It's expected
to be ORed value with some enumeration-constants, thus often it can not be
one of the enumeration-constants. I understood that this is out of
specification and causes implementation-dependent issues.

In C language specification, enumerated type can be interpreted as an
integer type, in which all of enumeration-constants in corresponding
enumerator-list can be stored. Implementations can select one of char,
signed int and unsigned int as its type, and this selection is
implementation-dependent.

In GCC, a signed integer is selected when at least one of
enumeration-constants has negative value, else an unsigned integer is
selected. This behaviour can be switched by -fshort-enums to short type.
Anyway, the type can be decided after scanning all of
enumeration-constants.

Totally, there's no rules to constrain the value of enumerated type to
be one of enumeration-constants. In short, in enumerated type, decision
of actual type for the type is the most important and
enumeration-constants are just used for the decision, thus it's permitted
to have an integer value in a range of enumeration-constants. In our case,
actual type for the type is currently deterministic to be either char or
unsigned int. Under GCC, it's unsigned int.

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

parent 13a6c832

sound/firewire/amdtp-stream.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -69,7 +69,7 @@ static void pcm_period_tasklet(unsigned long data);
		* @protocol_size: the size to allocate newly for protocol
		*/
		int amdtp_stream_init(struct amdtp_stream s, struct fw_unit unit,
		enum amdtp_stream_direction dir, int flags,
		enum amdtp_stream_direction dir, enum cip_flags flags,
		unsigned int fmt,
		amdtp_stream_process_data_blocks_t process_data_blocks,
		unsigned int protocol_size)

sound/firewire/amdtp-stream.h

+2 −2

Original line number	Diff line number	Diff line
		@@ -93,7 +93,7 @@ typedef unsigned int (*amdtp_stream_process_data_blocks_t)(
		unsigned int *syt);
		struct amdtp_stream {
		struct fw_unit *unit;
		int flags;
		enum cip_flags flags;
		enum amdtp_stream_direction direction;
		struct mutex mutex;

		@@ -137,7 +137,7 @@ struct amdtp_stream {
		};

		int amdtp_stream_init(struct amdtp_stream s, struct fw_unit unit,
		enum amdtp_stream_direction dir, int flags,
		enum amdtp_stream_direction dir, enum cip_flags flags,
		unsigned int fmt,
		amdtp_stream_process_data_blocks_t process_data_blocks,
		unsigned int protocol_size);