[PATCH] ASoC: SOF: control: override volume info callback

[PATCH] ASoC: SOF: control: override volume info callback

[Kai Vehmanen]

From: Jaska Uimonen <jaska.uimonen@linux.intel.com>

ASoC dapm controls currently don't support more than 2 channels. This is
a problem for SOF-based devices where individual volume control cannot
be provided on the 4 DMIC input path.

If we want to provide controls for more than 2 channels, this patch
suggests a simple solution based on an override of the info callback.
For example, in the case with 4 channel DMIC PGAs, a sof_info callback
would be used. Mono and stereo cases will keep using the existing dapm
info callback.

A longer-term solution would be to remove the limits to 2 channels in
ASoC/DAPM/topology. This is a topic Intel is currently looking into,
e.g. by removing the use of 'reg' and 'rreg' fields and use arrays
instead. Such changes will be rather intrusive and touch multiple codec
and platform drivers. Removing restrictions is the right thing to do,
but this will need to be done in steps with lots of validation.

Signed-off-by: Jaska Uimonen <jaska.uimonen@linux.intel.com>
Reviewed-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>
---
 sound/soc/sof/control.c   | 22 ++++++++++++++++++++++
 sound/soc/sof/sof-audio.h |  2 ++
 sound/soc/sof/topology.c  |  9 +++++++++
 3 files changed, 33 insertions(+)

diff --git a/sound/soc/sof/control.c b/sound/soc/sof/control.c
index 056c86ad5a47..a5dd728c580a 100644
--- a/sound/soc/sof/control.c
+++ b/sound/soc/sof/control.c
@@ -114,6 +114,28 @@ int snd_sof_volume_put(struct snd_kcontrol *kcontrol,
 	return change;
 }
 
+int snd_sof_volume_info(struct snd_kcontrol *kcontrol, struct snd_ctl_elem_info *uinfo)
+{
+	struct soc_mixer_control *sm = (struct soc_mixer_control *)kcontrol->private_value;
+	struct snd_sof_control *scontrol = sm->dobj.private;
+	unsigned int channels = scontrol->num_channels;
+	int platform_max;
+
+	if (!sm->platform_max)
+		sm->platform_max = sm->max;
+	platform_max = sm->platform_max;
+
+	if (platform_max == 1 && !strstr(kcontrol->id.name, " Volume"))
+		uinfo->type = SNDRV_CTL_ELEM_TYPE_BOOLEAN;
+	else
+		uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
+
+	uinfo->count = channels;
+	uinfo->value.integer.min = 0;
+	uinfo->value.integer.max = platform_max - sm->min;
+	return 0;
+}
+
 int snd_sof_switch_get(struct snd_kcontrol *kcontrol,
 		       struct snd_ctl_elem_value *ucontrol)
 {
diff --git a/sound/soc/sof/sof-audio.h b/sound/soc/sof/sof-audio.h
index 9f645a2e5a6c..ddcfd46617f8 100644
--- a/sound/soc/sof/sof-audio.h
+++ b/sound/soc/sof/sof-audio.h
@@ -124,6 +124,8 @@ int snd_sof_volume_get(struct snd_kcontrol *kcontrol,
 		       struct snd_ctl_elem_value *ucontrol);
 int snd_sof_volume_put(struct snd_kcontrol *kcontrol,
 		       struct snd_ctl_elem_value *ucontrol);
+int snd_sof_volume_info(struct snd_kcontrol *kcontrol,
+			struct snd_ctl_elem_info *ucontrol);
 int snd_sof_switch_get(struct snd_kcontrol *kcontrol,
 		       struct snd_ctl_elem_value *ucontrol);
 int snd_sof_switch_put(struct snd_kcontrol *kcontrol,
diff --git a/sound/soc/sof/topology.c b/sound/soc/sof/topology.c
index 44fddeda6043..b0132fa56fe2 100644
--- a/sound/soc/sof/topology.c
+++ b/sound/soc/sof/topology.c
@@ -1041,6 +1041,15 @@ static int sof_control_load_volume(struct snd_soc_component *scomp,
 		goto out;
 	}
 
+	/*
+	 * If control has more than 2 channels we need to override the info. This is because even if
+	 * ASoC layer has defined topology's max channel count to SND_SOC_TPLG_MAX_CHAN = 8, the
+	 * pre-defined dapm control types (and related functions) creating the actual control
+	 * restrict the channels only to mono or stereo.
+	 */
+	if (le32_to_cpu(mc->num_channels) > 2)
+		kc->info = snd_sof_volume_info;
+
 	/* init the volume get/put data */
 	scontrol->size = struct_size(scontrol->control_data, chanv,
 				     le32_to_cpu(mc->num_channels));
-- 
2.28.0

Re: [PATCH] ASoC: SOF: control: override volume info callback

[Mark Brown]

On Wed, 11 Nov 2020 19:31:05 +0200, Kai Vehmanen wrote:
> ASoC dapm controls currently don't support more than 2 channels. This is
> a problem for SOF-based devices where individual volume control cannot
> be provided on the 4 DMIC input path.
> 
> If we want to provide controls for more than 2 channels, this patch
> suggests a simple solution based on an override of the info callback.
> For example, in the case with 4 channel DMIC PGAs, a sof_info callback
> would be used. Mono and stereo cases will keep using the existing dapm
> info callback.
> 
> [...]

Applied to

   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound.git for-next

Thanks!

[1/1] ASoC: SOF: control: override volume info callback
      commit: fca18e62984a0d797da8379a422a6bb644d68244

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark