[alsa-devel] [PATCH 4/5] ASoC: dapm: Add support for autodisable mux controls

[Lars-Peter Clausen]

On 04/30/2015 05:00 PM, Charles Keepax wrote:
> On Thu, Apr 30, 2015 at 02:44:40PM +0200, Lars-Peter Clausen wrote:
>> On 04/30/2015 12:38 PM, Charles Keepax wrote:
>>> Commit 57295073b6ac ("ASoC: dapm: Implement mixer input auto-disable")
>>> added support for autodisable controls, controls whose values are only
>>> written to the hardware when their respective widgets are powered up.
>>> But it only added support for controls based on the mixer abstraction.
>>>
>>> This patch add support for mux controls (DAPM controls based on the
>>> enum abstraction) to be auto-disabled as well. As each mux can only have
>>> a single control, there is no need to tie the autodisable widget to the
>>> inputs (as is done for the mixer controls) it can be tided directly to
>>> the mux widget itself.
>>>
>>> Signed-off-by: Charles Keepax <ckeepax at opensource.wolfsonmicro.com>
>>
>> Looks pretty good.
>>
>> [...]
>>> @@ -354,6 +355,34 @@ static int dapm_kcontrol_data_alloc(struct snd_soc_dapm_widget *widget,
>>>    			}
>>>    		}
>>>    		break;
>>> +	case snd_soc_dapm_mux:
>>> +		e = (struct soc_enum *)kcontrol->private_value;
>>> +
>>> +		if (e->autodisable) {
>>> +			struct snd_soc_dapm_widget template;
>>> +
>>> +			memset(&template, 0, sizeof(template));
>>> +			template.reg = e->reg;
>>> +			template.mask = e->mask << e->shift_l;
>>> +			template.shift = e->shift_l;
>>> +			template.off_val = 0;
>>
>> I've though about adding a auto-disable MUX type as well and the chip
>> were I wanted to use it has a non-zero power-off value. So I'd like to be
>> able to somehow specify this. We could for example put it at the end of
>> the values array. E.g.
>>
>> if (e->values)
>> 	template.off_val = e->values[e->items].
>> else
>> 	template.off_val = 0;
>>
>
> Thats a good point something I hadn't thought of. It seems
> reasonable that if the mux is autodisable that one of the states
> in the values array should be the disabled state. Either the
> first or last value would seem the reasonable choices. I would
> lean towards the first value, as this is already the case in the
> Arizona code :-).

Hm, right. What I had in mind is to not export the off state to userland, 
but I guess it makes sense to make it possible to select it explicitly since 
it is consistent with the auto-disable switches.

- Lars