> > That looks like an error caught by the ALSA conformance tool? > > What are the odds that we have a similar issue with the other broadwell > drivers which don't have a constraint on the number of channels either on > their 'System PCM' dailink? > > Thanks > -Pierre > Yes. That's why I am sending patch for this old BDW platform... So far as I know only 'buddy' supports 2/4-channel recording while other BDW Chrome products should support stereo recording only. Therefore, this defect should only be triggered by the ALSA conformance tool. I am think about implementing the constraint in FE DAI's startup() callback instead of DAI Link's callback. Since the channels_max is 4 for the capture stream, ALSA conformance tool will always test 3-channel recording on any platforms using this driver. Does it make sense to you? sound/soc/intel/haswell/sst-haswell-pcm.c: static struct snd_soc_dai_driver hsw_dais[] = { { .name = "System Pin", .id = HSW_PCM_DAI_ID_SYSTEM, .playback = { .stream_name = "System Playback", .channels_min = 2, .channels_max = 2, .rates = SNDRV_PCM_RATE_48000, .formats = SNDRV_PCM_FMTBIT_S24_LE | SNDRV_PCM_FMTBIT_S16_LE, }, .capture = { .stream_name = "Analog Capture", .channels_min = 2, .channels_max = 4, .rates = SNDRV_PCM_RATE_48000, .formats = SNDRV_PCM_FMTBIT_S24_LE | SNDRV_PCM_FMTBIT_S16_LE, }, }, Regards, Brent