> -----Original Message----- > From: Pierre-Louis Bossart [mailto:pierre-louis.bossart@xxxxxxxxxxxxxxx] > Sent: Tuesday, September 10, 2019 1:53 AM > To: Lu, Brent <brent.lu@xxxxxxxxx>; alsa-devel@xxxxxxxxxxxxxxxx > Cc: Rojewski, Cezary <cezary.rojewski@xxxxxxxxx>; > kuninori.morimoto.gx@xxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; > yang.jie@xxxxxxxxxxxxxxx; tiwai@xxxxxxxx; liam.r.girdwood@xxxxxxxxxxxxxxx; > broonie@xxxxxxxxxx; tglx@xxxxxxxxxxxxx > Subject: Re: [PATCH] ASoC: bdw-rt5677: channel constraint > support > > Please don't top-post on public mailing lists. > > > We are working on a backport 3.14 branch for Chrome projects based on > BDW platform. In the branch 4-channel capture is supported on some > platforms but not all. So we need to add a constraint in the machine driver > for machines don't support this feature. > > > > I checked the for-next branch in the broonie repo. The channels_max of > HSW_PCM_DAI_ID_SYSTEM is 4 for capture stream so I think it would have > same issue like google's backport tree. I didn't find any constraint for this dai. > Would you point out where it is? > > > > .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, > > }, > > ok, I missed this capture case indeed, but when I look at the Chrome > 3.14 code I don't see this constraint being added, and we already have an > ssp0_fixup function where 2 channels only are used. > > /* The ADSP will covert the FE rate to 48k, stereo */ > rate->min = rate->max = 48000; > channels->min = channels->max = 2; Yes I noticed it, but the channel max number returned by snd_pcm_hw_params_any() is still 4 for the port "Capture PCM" so I add a constraint to the FE dai. > > I also don't see any case where we support 4 channels in any broadwell > machine driver? It's the bdw-rt5650.c which only exists in chrome's 3.14 branch supporting Buddy project. They submitted the machine driver but not yet merged. https://patchwork.kernel.org/patch/11050985/ > > So again can you point me to an issue or existing backport that requires the > patch below. Not trying to be obtuse but we should only change older > platforms when there is evidence that a change is needed. The story is Chrome has a tool called alsa_conformance_test which runs capture or playback against a PCM port with all possible configurations (channel, format, rate) then measure if the sample rate is correct. Since the channel max number reported is 4, it tests the 4-channel 48K capture and reports the actual sample rate is 24000 instead of 48000. That's the reason we want to add a constraint in machine driver to avoid user space programs trying to do 4 channel recording since this machine does not support it in the beginning. > > -Pierre > > > > > Regards, > > Brent Lu > > > > -----Original Message----- > > From: Pierre-Louis Bossart > > [mailto:pierre-louis.bossart@xxxxxxxxxxxxxxx] > > Sent: Friday, September 6, 2019 10:21 PM > > To: Lu, Brent <brent.lu@xxxxxxxxx>; alsa-devel@xxxxxxxxxxxxxxxx > > Cc: Rojewski, Cezary <cezary.rojewski@xxxxxxxxx>; > > liam.r.girdwood@xxxxxxxxxxxxxxx; yang.jie@xxxxxxxxxxxxxxx; > > broonie@xxxxxxxxxx; perex@xxxxxxxx; tiwai@xxxxxxxx; > > kuninori.morimoto.gx@xxxxxxxxxxx; tglx@xxxxxxxxxxxxx; > > linux-kernel@xxxxxxxxxxxxxxx > > Subject: Re: [PATCH] ASoC: bdw-rt5677: channel constraint > > support > > > > On 9/5/19 8:24 PM, Brent Lu wrote: > >> BDW boards using this machine driver supports only stereo capture and > >> playback. Implement a constraint to enforce it. > > > > Humm, can you clarify what problem/error this patch fixes? > > > > There are already constraints on the hsw_dais[] where the channels are > stereo only. > > > > Thanks > > -Pierre > > > >> > >> Signed-off-by: Brent Lu <brent.lu@xxxxxxxxx> > >> --- > >> sound/soc/intel/boards/bdw-rt5677.c | 33 > +++++++++++++++++++++++++++++++++ > >> 1 file changed, 33 insertions(+) > >> > >> diff --git a/sound/soc/intel/boards/bdw-rt5677.c > >> b/sound/soc/intel/boards/bdw-rt5677.c > >> index 4a4d335..a312b55 100644 > >> --- a/sound/soc/intel/boards/bdw-rt5677.c > >> +++ b/sound/soc/intel/boards/bdw-rt5677.c > >> @@ -22,6 +22,8 @@ > >> > >> #include "../../codecs/rt5677.h" > >> > >> +#define DUAL_CHANNEL 2 > >> + > >> struct bdw_rt5677_priv { > >> struct gpio_desc *gpio_hp_en; > >> struct snd_soc_component *component; @@ -245,6 +247,36 @@ > static > >> int bdw_rt5677_init(struct snd_soc_pcm_runtime *rtd) > >> return 0; > >> } > >> > >> +static const unsigned int channels[] = { > >> + DUAL_CHANNEL, > >> +}; > >> + > >> +static const struct snd_pcm_hw_constraint_list constraints_channels = { > >> + .count = ARRAY_SIZE(channels), > >> + .list = channels, > >> + .mask = 0, > >> +}; > >> + > >> +static int bdw_fe_startup(struct snd_pcm_substream *substream) { > >> + struct snd_pcm_runtime *runtime = substream->runtime; > >> + > >> + /* > >> + * On this platform for PCM device we support, > >> + * stereo > >> + */ > >> + > >> + runtime->hw.channels_max = DUAL_CHANNEL; > >> + snd_pcm_hw_constraint_list(runtime, 0, > SNDRV_PCM_HW_PARAM_CHANNELS, > >> + &constraints_channels); > >> + > >> + return 0; > >> +} > >> + > >> +static const struct snd_soc_ops bdw_rt5677_fe_ops = { > >> + .startup = bdw_fe_startup, > >> +}; > >> + > >> /* broadwell digital audio interface glue - connects codec <--> CPU */ > >> SND_SOC_DAILINK_DEF(dummy, > >> DAILINK_COMP_ARRAY(COMP_DUMMY())); > >> @@ -273,6 +305,7 @@ static struct snd_soc_dai_link bdw_rt5677_dais[] = > { > >> }, > >> .dpcm_capture = 1, > >> .dpcm_playback = 1, > >> + .ops = &bdw_rt5677_fe_ops, > >> SND_SOC_DAILINK_REG(fe, dummy, platform), > >> }, > >> > >> > > > > _______________________________________________ > > Alsa-devel mailing list > > Alsa-devel@xxxxxxxxxxxxxxxx > > https://mailman.alsa-project.org/mailman/listinfo/alsa-devel > > _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx https://mailman.alsa-project.org/mailman/listinfo/alsa-devel
