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ALSA: usb-audio: work around streaming quirk for MacroSilicon MS2109
authorHector Martin <marcan@marcan.st>
Mon, 10 Aug 2020 08:24:00 +0000 (17:24 +0900)
committerTakashi Iwai <tiwai@suse.de>
Mon, 10 Aug 2020 10:57:12 +0000 (12:57 +0200)
commit1b7ecc241a67ad6b584e071bd791a54e0cd5f097
treef3f50d33541982032c151bfe33a91378584f1120
parent386a6539992b82fe9ac4f9dc3f548956fd894d8c
ALSA: usb-audio: work around streaming quirk for MacroSilicon MS2109

Further investigation of the L-R swap problem on the MS2109 reveals that
the problem isn't that the channels are swapped, but rather that they
are swapped and also out of phase by one sample. In other words, the
issue is actually that the very first frame that comes from the hardware
is a half-frame containing only the right channel, and after that
everything becomes offset.

So introduce a new quirk field to drop the very first 2 bytes that come
in after the format is configured and a capture stream starts. This puts
the channels in phase and in the correct order.

Cc: stable@vger.kernel.org
Signed-off-by: Hector Martin <marcan@marcan.st>
Link: https://lore.kernel.org/r/20200810082400.225858-1-marcan@marcan.st
Signed-off-by: Takashi Iwai <tiwai@suse.de>
sound/usb/card.h
sound/usb/pcm.c
sound/usb/quirks.c
sound/usb/stream.c