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: Adam Goode agoode@google.com

diff --git a/sound/usb/clock.c b/sound/usb/clock.c index c79749613fa6..db5e39d67a90 100644 --- a/sound/usb/clock.c +++ b/sound/usb/clock.c @@ -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) - return clock; + 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; }