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Commit 58cabe87 authored by Adam Goode's avatar Adam Goode Committed by Takashi Iwai
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ALSA: usb-audio: Allow changing from a bad sample rate 



If the audio device is externally clocked and set to a rate that does
not match the external clock, the clock will never be valid and we cannot
set the rate successfully. To fix this, allow a rate change even if
the clock is initially invalid, and validate again after the rate is
changed.

This fixes problems with MOTU UltraLite AVB hardware over USB.

Signed-off-by: default avatarAdam Goode <agoode@google.com>
Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parent 67ece13f

sound/usb/clock.c

+21 −3
Original line number Diff line number Diff line
@@ -513,14 +513,28 @@ static int set_sample_rate_v2v3(struct snd_usb_audio *chip, int iface, 
	bool writeable;

	u32 bmControls;



	/* First, try to find a valid clock. This may trigger

	 * automatic clock selection if the current clock is not

	 * valid.

	 */

	clock = snd_usb_clock_find_source(chip, fmt->protocol,

					  fmt->clock, true);

	if (clock < 0) {

		/* We did not find a valid clock, but that might be

		 * because the current sample rate does not match an

		 * external clock source. Try again without validation

		 * and we will do another validation after setting the

		 * rate.

		 */

		clock = snd_usb_clock_find_source(chip, fmt->protocol,

						  fmt->clock, false);

		if (clock < 0)

			return clock;

	}



	prev_rate = get_sample_rate_v2v3(chip, iface, fmt->altsetting, clock);

	if (prev_rate == rate)

		return 0;

		goto validation;



	if (fmt->protocol == UAC_VERSION_3) {

		struct uac3_clock_source_descriptor *cs_desc;
@@ -577,6 +591,10 @@ static int set_sample_rate_v2v3(struct snd_usb_audio *chip, int iface, 
		snd_usb_set_interface_quirk(dev);

	}



validation:

	/* validate clock after rate change */

	if (!uac_clock_source_is_valid(chip, fmt->protocol, clock))

		return -ENXIO;

	return 0;

}