[alsa-devel] [RFC 0/5] Add a gpio jack device

[Lars-Peter Clausen]

On 05/27/2015 06:22 AM, Dylan Reid wrote:
> On Tue, May 26, 2015 at 1:14 PM, Mark Brown <broonie at kernel.org> wrote:
>> On Tue, May 26, 2015 at 08:43:34PM +0200, Lars-Peter Clausen wrote:
>>> On 05/25/2015 07:15 PM, Mark Brown wrote:
>>
>>>> I think it solves the 90% case well enough for simple-card (which is to
>>>> the main target user here) and the situation with jack detection is
>>>> already fragmented enough that we're not likely to make things
>>>> that much worse.  Though now I think about it just taking the gpio out
>>>> of the device name would help with binding reuse for other users.
>>
>>> Yea, but 90% of those 90% are already covered by the existing bindings. The
>>
>> I'm not sure what this thing with "yea" is (I've seen some other people
>> use it too) but the normal word is "yes"...
>>
>>> existing simple-card bindings and driver support GPIO based jack detection,
>>> albeit not as flexible as this. But we don't actually gain that much with
>>
>> Huh, so they do.  Ugh.
>>
>>>> Yes, this is the complete solution - and it's not an audio specific
>>>> thing either, there's a reasonable case to be made for saying that that
>>>> this should be resolved in extcon rather than in any one consumer
>>>> subsystem.
>>
>>> If the bindings are good it doesn't really matter which framework eventually
>>> picks them up, but in this case the bindings are awfully ASoC specific and
>>> leak a lot of the shortcomings of the current implementation.
>>
>> Could you expand on the abstraction problems you see please?  It looks
>> like a fairly direct mapping of GPIOs to a jack to me (like I say I
>> don't see having GPIOs directly on the jack object as a problem - having
>> to create a separate node to put the GPIOs in doesn't seem to solve
>> anything) and we're not likely to have enough GPIOs to make the usual
>> problems with lists of values too severe.
>>
>> The only things that concerned me particularly were the name (which I
>> did agree on once you mentioned it) and the use of a bitmask to describe
>> what's being reported but it's hard to think of anything much better
>> than that.
>
> Is just "audio-jack" too generic?  There are a lot of audio jacks that
> wouldn't be described by this binding, such as those reported by the
> 227e or 5650.  The original goal here was to describe a jack that has
> one or more gpios, each representing a particular type of device being
> attached.  This doesn't overlap with the binding for a jack that is
> handled by a headset detect chip.  Does this seem like the right goal,
> or is there a benefit to having an "audio-jack" binding that tries to
> cover all different types of jacks?

Ideally we'd have a binding which is generic enough to cover not only audio 
jacks but be a bit more generic. I think Laurent already has some thoughts 
on how such a binding should look like.

- Lars