For devices with multiple clock sources connected to a selector, we need to check what a clock selector control request has returned. This is needed to ensure that a requested clock source is indeed selected and for autoclock feature to work.
For devices with single clock source connected, if we get an error there is nothing else we can do about it. We can't skip clock selector setup as it is required by some devices. So lets just ignore error in this case.
This should fix various buggy Mackie devices:
[ 649.109785] usb 1-1.3: parse_audio_format_rates_v2v3(): unable to find clock source (clock -32) [ 649.111946] usb 1-1.3: parse_audio_format_rates_v2v3(): unable to find clock source (clock -32) [ 649.113822] usb 1-1.3: parse_audio_format_rates_v2v3(): unable to find clock source (clock -32)
There is also interesting info from the Windows documentation [1] (this is probably why manufacturers dont't even test this feature):
"The USB Audio 2.0 driver doesn't support clock selection. The driver uses the Clock Source Entity, which is selected by default and never issues a Clock Selector Control SET CUR request."
Link: https://learn.microsoft.com/en-us/windows-hardware/drivers/audio/usb-2-0-aud... [1] Link: https://bugzilla.kernel.org/show_bug.cgi?id=217314 Link: https://bugzilla.kernel.org/show_bug.cgi?id=218175 Link: https://bugzilla.kernel.org/show_bug.cgi?id=218342 Signed-off-by: Alexander Tsoy alexander@tsoy.me --- sound/usb/clock.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/sound/usb/clock.c b/sound/usb/clock.c index a8204c6d6fac..60fcb872a80b 100644 --- a/sound/usb/clock.c +++ b/sound/usb/clock.c @@ -347,8 +347,16 @@ static int __uac_clock_find_source(struct snd_usb_audio *chip, !writeable) return ret; err = uac_clock_selector_set_val(chip, entity_id, cur); - if (err < 0) + if (err < 0) { + if (pins == 1) { + usb_audio_dbg(chip, + "%s(): selector returned an error, " + "assuming a firmware bug, id %d, ret %d\n", + __func__, clock_id, err); + return ret; + } return err; + } }
if (!validate || ret > 0 || !chip->autoclock)