Re: [PATCH RFC 0/9] gpio: improve support for shared GPIOs

[Srinivas Kandagatla <srini@kernel.org>]

On 10/6/25 5:10 PM, Bartosz Golaszewski wrote:
> On Mon, Oct 6, 2025 at 5:43 PM Manivannan Sadhasivam <mani@kernel.org> wrote:
>>
>> On Wed, Sep 24, 2025 at 11:25:12AM -0700, Dmitry Torokhov wrote:
>>> Hi Bartosz,
>>>
>>>>
>>>> The practical use-case for this are the powerdown GPIOs shared by
>>>> speakers on Qualcomm db845c platform, however I have also extensively
>>>> tested it using gpio-virtuser on arm64 qemu with various DT
>>>> configurations.
>>>
>>> How is this different from the existing gpio-backed regulator/supply?
>>> IMO GPIOs are naturally exclusive-use resources (in cases when you need
>>> to control them, not simply read their state), and when there is a need
>>> to share them there are more appropriate abstractions that are built on
>>> top of GPIOs...
>>>
>>
>> Not always... For something like shared reset line, consumers request the line
>> as GPIO and expect gpiolib to do resource manangement.
>>
> 
> They could use the reset API and it would implicitly create a virtual
> device that requests the reset GPIO and controls its enable count.
> Except that some devices also do a specific reset sequence with delays
> etc. That would require some additional logic in reset-gpio.
That should be a platform specific reset controller driver.

> 
> Bart