Re: [PATCH v5 12/13] ASoC: codecs: Add support for the generic IIO auxiliary devices

[Jonathan Cameron <jic23@kernel.org>]

On Thu, 15 Jun 2023 17:26:30 +0200
Herve Codina <herve.codina@bootlin.com> wrote:

> Industrial I/O devices can be present in the audio path.
> These devices needs to be used as audio components in order to be
> fully integrated in the audio path.
> 
> This support allows to consider these Industrial I/O devices as
> auxiliary audio devices and allows one to control them using mixer
> controls.
> 
> Signed-off-by: Herve Codina <herve.codina@bootlin.com>

A few trivial things inline.
With those tidied up, (for the IIO bits and general code - but I don't know
the snd part well enough to review that).

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

> index 000000000000..b9d72cbb85f2
> --- /dev/null
> +++ b/sound/soc/codecs/audio-iio-aux.c
> @@ -0,0 +1,338 @@

...

> +static int audio_iio_aux_add_controls(struct snd_soc_component *component,
> +				      struct audio_iio_aux_chan *chan)
> +{
> +	struct snd_kcontrol_new control = {};

Why not:

	struct snd_kcontrol_new control = {
		.iface = SNDRV_CTL_ELEM_IFACE_MIXER;
		.name = chan->name;
		.info = audio_iio_aux_info_volsw;
		.get = audio_iio_aux_get_volsw;
		.put = audio_iio_aux_put_volsw;
		.private_value = (unsigned long)chan;
	};

> +
> +	control.iface = SNDRV_CTL_ELEM_IFACE_MIXER;
> +	control.name = chan->name;
> +	control.info = audio_iio_aux_info_volsw;
> +	control.get = audio_iio_aux_get_volsw;
> +	control.put = audio_iio_aux_put_volsw;
> +	control.private_value = (unsigned long)chan;
> +
> +	return snd_soc_add_component_controls(component, &control, 1);
> +}
> +
> +/*
> + * These data could be on stack but they are pretty big.
> + * As ASoC internally copy them and protect them against concurrent accesses
> + * (snd_soc_bind_card() protects using client_mutex), keep them in the global
> + * data area.
> + */
> +static struct snd_soc_dapm_widget widgets[3];
> +static struct snd_soc_dapm_route routes[2];
> +
> +/* Be sure sizes are correct (need 3 widgets and 2 routes) */
> +static_assert(ARRAY_SIZE(widgets) >= 3, "3 widgets are needed");
> +static_assert(ARRAY_SIZE(routes) >= 2, "2 routes are needed");
> +
> +static int audio_iio_aux_add_dapms(struct snd_soc_component *component,
> +				   struct audio_iio_aux_chan *chan)
> +{
> +	struct snd_soc_dapm_context *dapm = snd_soc_component_get_dapm(component);
> +	char *output_name;
> +	char *input_name;
> +	char *pga_name;
> +	int ret;
> +
> +	input_name = kasprintf(GFP_KERNEL, "%s IN", chan->name);
> +	if (!input_name)
> +		return -ENOMEM;
> +
> +	output_name = kasprintf(GFP_KERNEL, "%s OUT", chan->name);
> +	if (!output_name) {
> +		ret = -ENOMEM;
> +		goto out_free_input_name;
> +	}

Trivial but a blank line here would be nice.

> +	pga_name = kasprintf(GFP_KERNEL, "%s PGA", chan->name);
> +	if (!pga_name) {
> +		ret = -ENOMEM;
> +		goto out_free_output_name;
> +	}
> +
> +	widgets[0] = SND_SOC_DAPM_INPUT(input_name);
> +	widgets[1] = SND_SOC_DAPM_OUTPUT(output_name);
> +	widgets[2] = SND_SOC_DAPM_PGA(pga_name, SND_SOC_NOPM, 0, 0, NULL, 0);
> +	ret = snd_soc_dapm_new_controls(dapm, widgets, 3);
> +	if (ret)
> +		goto out_free_pga_name;
> +
> +	routes[0].sink = pga_name;
> +	routes[0].control = NULL;
> +	routes[0].source = input_name;
> +	routes[1].sink = output_name;
> +	routes[1].control = NULL;
> +	routes[1].source = pga_name;
> +	ret = snd_soc_dapm_add_routes(dapm, routes, 2);
> +
> +	/* Allocated names are no more needed (duplicated in ASoC internals) */
> +
> +out_free_pga_name:
> +	kfree(pga_name);
> +out_free_output_name:
> +	kfree(output_name);
> +out_free_input_name:
> +	kfree(input_name);
> +	return ret;
> +}
> +
> +static int audio_iio_aux_component_probe(struct snd_soc_component *component)
> +{
> +	struct audio_iio_aux *iio_aux = snd_soc_component_get_drvdata(component);
> +	struct audio_iio_aux_chan *chan;
> +	int ret;
> +	int i;
> +
> +	for (i = 0; i < iio_aux->num_chans; i++) {
> +		chan = iio_aux->chans + i;
> +
> +		ret = iio_read_max_channel_raw(chan->iio_chan, &chan->max);
> +		if (ret)
> +			return dev_err_probe(component->dev, ret,
> +					     "chan[%d] %s: Cannot get max raw value\n",
> +					     i, chan->name);
> +
> +		ret = iio_read_min_channel_raw(chan->iio_chan, &chan->min);
> +		if (ret)
> +			return dev_err_probe(component->dev, ret,
> +					     "chan[%d] %s: Cannot get min raw value\n",
> +					     i, chan->name);
> +
> +		if (chan->min > chan->max) {
> +			dev_dbg(component->dev, "chan[%d] %s: Swap min and max\n",
> +				i, chan->name);

Why?  I'd like a comment here on what circumstances could cause this to happen.

> +			swap(chan->min, chan->max);
> +		}
> +
> +		/* Set initial value */
> +		ret = iio_write_channel_raw(chan->iio_chan,
> +					    chan->is_invert_range ? chan->max : chan->min);
> +		if (ret)
> +			return dev_err_probe(component->dev, ret,
> +					     "chan[%d] %s: Cannot set initial value\n",
> +					     i, chan->name);
> +
> +		ret = audio_iio_aux_add_controls(component, chan);
> +		if (ret)
> +			return ret;
> +
> +		ret = audio_iio_aux_add_dapms(component, chan);
> +		if (ret)
> +			return ret;
> +
> +		dev_dbg(component->dev, "chan[%d]: Added %s (min=%d, max=%d, invert=%s)\n",
> +			i, chan->name, chan->min, chan->max,
> +			str_on_off(chan->is_invert_range));
> +	}
> +
> +	return 0;
> +}