On Mon, Feb 17, 2020 at 03:43:01PM +0000, Mark Brown wrote:
> On Mon, Feb 17, 2020 at 03:41:20PM +0100, Stephan Gerhold wrote:
>
> > I'm a bit confused about this patch, isn't SNDRV_PCM_STREAM_PLAYBACK
> > used for both cpu_dai and codec_dai in the playback case?
>
> It is in the normal case, but with a CODEC<->CODEC link (which was what
> this was targeting) we need to bodge things by swapping playback and
> capture on one end of the link.
I see. Looking at the code again I'm guessing the cause of the crash
"fixed" by this patch is commit a342031cdd08 ("ASoC: create pcm for
codec2codec links as well") where the codec2codec case was sort of
patched in. This is what we had before this patch:
/* Adapt stream for codec2codec links */
struct snd_soc_pcm_stream *cpu_capture = rtd->dai_link->params ?
&cpu_dai->driver->playback : &cpu_dai->driver->capture;
struct snd_soc_pcm_stream *cpu_playback = rtd->dai_link->params ?
&cpu_dai->driver->capture : &cpu_dai->driver->playback;
This does the swapping you mentioned, so I guess rtd->dai_link->params
is only set for the codec2codec case?
for_each_rtd_codec_dai(rtd, i, codec_dai) {
if (snd_soc_dai_stream_valid(codec_dai, SNDRV_PCM_STREAM_PLAYBACK) &&
snd_soc_dai_stream_valid(cpu_dai, SNDRV_PCM_STREAM_PLAYBACK))
playback = 1;
if (snd_soc_dai_stream_valid(codec_dai, SNDRV_PCM_STREAM_CAPTURE) &&
snd_soc_dai_stream_valid(cpu_dai, SNDRV_PCM_STREAM_CAPTURE))
capture = 1;
}
capture = capture && cpu_capture->channels_min;
playback = playback && cpu_playback->channels_min;
And this does a part of the check in snd_soc_dai_stream_valid(),
but without the NULL check of cpu_capture/cpu_playback.
(Maybe that is the cause of the crash.)
>From my limited understanding, I would say that a much simpler way to
implement this would be:
/* Adapt stream for codec2codec links */
int cpu_capture = rtd->dai_link->params ?
SNDRV_PCM_STREAM_PLAYBACK : SNDRV_PCM_STREAM_CAPTURE;
int cpu_playback = rtd->dai_link->params ?
SNDRV_PCM_STREAM_CAPTURE : SNDRV_PCM_STREAM_PLAYBACK;
for_each_rtd_codec_dai(rtd, i, codec_dai) {
if (snd_soc_dai_stream_valid(codec_dai, SNDRV_PCM_STREAM_PLAYBACK) &&
snd_soc_dai_stream_valid(cpu_dai, cpu_playback))
playback = 1;
if (snd_soc_dai_stream_valid(codec_dai, SNDRV_PCM_STREAM_CAPTURE) &&
snd_soc_dai_stream_valid(cpu_dai, cpu_capture))
capture = 1;
}
since snd_soc_dai_stream_valid() does both the NULL-check and the
"channels_min" check.
But I'm really not familar with the codec2codec case and am unable to
test it :) What do you think?
Thanks,
Stephan
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