В Пн, 29/06/2020 в 11:37 -0400, Sasha Levin пишет: > From: Alexander Tsoy <alexander@xxxxxxx> > > [ Upstream commit f0bd62b64016508938df9babe47f65c2c727d25c ] > > For computation of the the next frame size current value of fs/fps > and > accumulated fractional parts of fs/fps are used, where values are > stored > in Q16.16 format. This is quite natural for computing frame size for > asynchronous endpoints driven by explicit feedback, since in this > case > fs/fps is a value provided by the feedback endpoint and it's already > in > the Q format. If an error is accumulated over time, the device can > adjust fs/fps value to prevent buffer overruns/underruns. > > But for synchronous endpoints the accuracy provided by these > computations > is not enough. Due to accumulated error the driver periodically > produces > frames with incorrect size (+/- 1 audio sample). > > This patch fixes this issue by implementing a different algorithm for > frame size computation. It is based on accumulating of the remainders > from division fs/fps and it doesn't accumulate errors over time. This > new method is enabled for synchronous and adaptive playback > endpoints. > > Signed-off-by: Alexander Tsoy <alexander@xxxxxxx> > Link: > https://lore.kernel.org/r/20200424022449.14972-1-alexander@xxxxxxx > Signed-off-by: Takashi Iwai <tiwai@xxxxxxx> > Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> > --- > sound/usb/card.h | 4 ++++ > sound/usb/endpoint.c | 43 ++++++++++++++++++++++++++++++++++++++-- > --- > sound/usb/endpoint.h | 1 + > sound/usb/pcm.c | 2 ++ > 4 files changed, 45 insertions(+), 5 deletions(-) Please drop this patch from the queue for now (and for 4.4 as well). It introduced a regression for some devices. The fix is available, but not accepted yet.
