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

[Manivannan Sadhasivam]

On Mon, Oct 06, 2025 at 06:10:59PM +0200, Bartosz Golaszewski wrote:
> On Mon, Oct 6, 2025 at 5:43 PM Manivannan Sadhasivam <mani at 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.
> 

I was referring to the PCIe PERST# line, for which the 'reset-gpios' property
already exist in the schema. Now, you want me to model this simple GPIO as a
fake reset controller and use it the PCIe Bridge nodes through 'resets'
property?

- Mani

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