On 9/12/22 14:42, Pierre-Louis Bossart wrote:
On 12/9/22 01:37, Péter Ujfalusi wrote:
On 08/12/2022 18:37, Pierre-Louis Bossart wrote:
On 12/8/22 10:17, Mark Brown wrote:
On Thu, Dec 08, 2022 at 02:02:02PM +0000, Joakim Tjernlund wrote:
Several of our Lenovo laptops lost PC audio output in Teams in 5.15.81(also in 5.15.82)
Revering above patch:https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=linux-5.15.y&id=b2ddd76237121155dcadfc4ae77ca1775dfc99f7
fixes it.
Any idea what the real fix is?
Adding the Intel people. I've no idea if there's issues with
dependencies, missing quirks for the hardare or anything in that stable
version.
Humm, yes in the past we used the TDM masks to convey the 'stream_tag'
for HDaudio.
I can still see this in v5.15.85 in sound/soc/sof/intel/hda-dai.c
/* set the stream tag in the codec dai dma params */
if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
snd_soc_dai_set_tdm_slot(codec_dai, stream_tag, 0, 0, 0);
else
snd_soc_dai_set_tdm_slot(codec_dai, 0, stream_tag, 0, 0);
That was changed in
636110411ca72 ASoC: Intel/SOF: use set_stream() instead of
set_tdm_slots() for HDAudio
snd_soc_dai_set_stream(codec_dai, hdac_stream(hext_stream),
substream->stream);
So my guess is that zeroing out TDM masks has a side effect on older
stable kernels, and that effect is not seen on newer kernels.
I don't really understand what the side effect might be though.
The reason is that on the the tdm mask now became persistent and the HDA
code relied on the fact that it is volatile, it is reset for each stream
open.
The core would do some fixup if the tx/rx_mask is set:
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/sound/soc/soc-pcm.c?h=linux-5.15.y&#n963
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/sound/soc/soc-pcm.c?h=linux-5.15.y&#n968
This did not happened when the tx/rx_mask was reset at open - and later
set bny the HDA driver, I guess after these checks, so the fixup did not
happened, but without resetting them we would use the previously set
masks to do fixups for the number of channels (!) based on a stream_tag
value, which has nothing to do with channels.
Agree with the analysis, so what would be the least bad recommendation?
a) revert the "don't zero TDM masks" patch
b) backport the change to use set_stream()?
Adding alsa-devel@xxxxxxxxxxxxxxxx and patches@xxxxxxxxxxxxxxxxxxxxx.
Please add relevant lists when sending emails so that other people who
might need to know, or have an opinion, are aware of the discussion.
