[alsa-devel] [PATCH 1/4] soc/sound: tegra_max98090: do not invert headphone jack

[Stephen Warren]

On 02/04/2016 12:17 PM, Dylan Reid wrote:
> On Thu, Feb 4, 2016 at 11:05 AM, Jonathan Tinkham <sctincman at gmail.com> wrote:
>> On 02/04/2016 09:36 AM, Stephen Warren wrote:
>>>
>>> On 02/03/2016 10:30 PM, Jonathan Tinkham wrote:
>>>>
>>>> The headphone jack should not be inverted
>>>
>>>
>>> Have you tested this on Venice2 as well as Nyan? I'm pretty sure Venice2
>>> was tested when this driver was written, and whoever added Nyan support to
>>> the kernel simply assumed it would work. As such, my suspicion is that this
>>> series will break Venice2 even as it fixes Nyan.
>>
>>
>> I have not tested this on Venice2, only on Nyan. That seems like a plausible
>> cause and reasonable suspicion.
>>
>>> Why doesn't user-space expect what the kernel actually implements? The
>>> kernel should be defining the control naming.
>>>
>>> Which user-space are you using specifically, and which part of it expects
>>> particular naming?
>>>
>>> Perhaps this series needs to be parametrized based on a flag in DT, rather
>>> than switching the hard-coded values, so that only Venice2 can be affected?
>>
>>
>> Specifically pulse-audio and alsa under Arch Linux.
>>
>> I was referencing 'Documentation/sound/alsa/soc/dapm.txt' with regards to
>> control names. While it is possible to add another entry into the user-space
>> configuration, I took this documentation as a definition of kernel control
>> naming schemes, and thought the driver had used a non-standard naming scheme
>> (or at least, not a consistent one).
>>
>>> On 02/03/2016 10:31 PM, Jonathan Tinkham wrote:
>>>>
>>>> Update device-tree bindings to reflect the rename of the board's
>>>> headphone jack.
>>>
>>>
>>> This looks like an incompatible change to the DT. While you've fixed the
>>> DT, which will fix new installations, old DTs now won't work. This breaks DT
>>> ABI. Any DT change needs to be backwards compatible, i.e. the old name
>>> should still work and be documented as a legacy value.
>>
>>
>> I see that now. If the inversion behavior differs between venice2 and nyan,
>> then another compatible string would need to be added anyways, correct? As
>> you mentioned above, this might need to be done anyways for the rename.
>
> Venice2 and both nyan platforms do have different polarity of HP detect.
>
> For some boards we have an hd-invert property in DT.
>
> Would setting hp-det-gpio to active low in the pinmux achieve the same thing?

I don't believe we have a pinmux setting for this.

However, there's a GPIO_ACTIVE_HIGH/LOW flag that could be used in DT 
property nvidia,hp-det-gpios's flags field to indicate the polarity. 
That should work, but indeed you could use a separate hp-dt-invert 
property if not.