linux-kernel - Re: [PATCH 01/14] mfd: arizona: Add jack pointer to struct arizona

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Message-ID: <f2c7d303-6137-4a02-a581-afd2ab6b1ca9@redhat.com>
Date:   Wed, 30 Dec 2020 13:01:52 +0100
From:   Hans de Goede <hdegoede@...hat.com>
To:     Richard Fitzgerald <rf@...nsource.cirrus.com>,
        Mark Brown <broonie@...nel.org>,
        Charles Keepax <ckeepax@...nsource.cirrus.com>
Cc:     Lee Jones <lee.jones@...aro.org>,
        MyungJoo Ham <myungjoo.ham@...sung.com>,
        Chanwoo Choi <cw00.choi@...sung.com>,
        Cezary Rojewski <cezary.rojewski@...el.com>,
        Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>,
        Liam Girdwood <liam.r.girdwood@...ux.intel.com>,
        Jie Yang <yang.jie@...ux.intel.com>,
        patches@...nsource.cirrus.com, linux-kernel@...r.kernel.org,
        alsa-devel@...a-project.org
Subject: Re: [PATCH 01/14] mfd: arizona: Add jack pointer to struct arizona

Hi,

On 12/30/20 12:23 PM, Richard Fitzgerald wrote:
> On 30/12/2020 11:04, Hans de Goede wrote:
>> Hi,
>>
>> On 12/29/20 5:51 PM, Richard Fitzgerald wrote:
>>>
>>>
>>> On 29/12/2020 15:40, Hans de Goede wrote:
>>>> Hi,
>>>>
>>>> On 12/29/20 4:15 PM, Mark Brown wrote:
>>>>> On Tue, Dec 29, 2020 at 03:06:35PM +0000, Charles Keepax wrote:
>>>>>
>>>>>> There is maybe more argument for porting the Arizona code across
>>>>>> anyways, since for a long time Android didn't properly support extcon
>>>>>> either. It supported the earlier out of tree switch stuff, extcon
>>>>>
>>>>> Completely moving the driver doesn't cause the same problems as the
>>>>> current proposal (unless it drops functionality I guess, there were
>>>>> issues with adding new detection types into the input layer but I can't
>>>>> remember if this hardware was impacted by that or not).
>>>>
>>>> The input-layer supports the following switches:
>>>>
>>>> SW_HEADPHONE_INSERT
>>>> SW_MICROPHONE_INSERT
>>>> SW_LINEOUT_INSERT
>>>> SW_JACK_PHYSICAL_INSERT
>>>>
>>>> Which is a 1:1 mapping with the cable-types currently exported by
>>>> extcon-arizona.c .
>>>>
>>>> I'm fine with fully moving extcon-arizona.c over to only using
>>>> sound/core/jack.c functionality and it no longer exporting an
>>>> extcon device.
>>>>
>>>> I guess we should move it out of drivers/extcon then though.
>>>> I suggest using: sound/soc/cirrus/arizona-jack-detect.c
>>>> Note that sound/soc/cirrus is a new dir here. Would that work
>>>> for you ?
>>>
>>> Shouldn't it be sound/soc/codecs/arizona-jack.c so that it is with all
>>> the other code for those codecs?
>>
>> The arizona codecs use the MFD framework and there is a separate
>> platform-device instantiated for the jack-detect functionality, so this
> 
> That is because it is an extcon driver. It is a different subsystem to
> the other child drivers so has to be a separate child.
> 
>> (mostly) a standalone platform-driver which has very little interaction
>> with the rest of the codec code.
>>
>> It is not a codec driver, or code shared between the codec drivers,
>> so putting it under sound/soc/codecs would be a bit weird.
>>
> 
> In fact it is tied into the codec driver. The code in arizona.c that
> handles HP OUT has to synchronize  with the jack detection to avoid one
> driver trashing the state of the other. But because they are currently
> separate drivers they have to communicate through hp_ena and
> hp_clamp in the parent mfd data. See arizona_hp_ev().

So what you are suggesting is to do something along these lines ? :

1. Drop the MFD instantiated arizona-extcon device
2. Move the extcon code to something more like a library
3. Have the various codec drivers call into the library
   at various points
4. Have the library call snd_soc_card_jack_new,
   snd_soc_jack_report, etc. ?

That works for me, but I would like to make sure we are all on
the same page here before spending time on coding this solution.

Regards,

Hans