On Mon, Feb 17, 2020 at 06:12:53PM +0100, Stephan Gerhold wrote:
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.)
Uh, no, I am completely wrong here. :) cpu_capture/cpu_playback cannot actually be NULL... I should have looked more carefully at snd_soc_dai_stream_valid()...
But I still wonder if the approach below would be easier?
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