Hi Pierre
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,
},
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),
> },
>
>
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