Messages in this thread | | | Date | Thu, 18 Jan 2018 16:22:28 +0100 | From | Ludovic Desroches <> | Subject | Re: [RFC PATCH 2/2] gpio: provide a consumer when requesting a gpio |
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On Thu, Jan 18, 2018 at 11:30:00AM +0100, Linus Walleij wrote: > On Mon, Jan 15, 2018 at 5:24 PM, Ludovic Desroches > <ludovic.desroches@microchip.com> wrote: > > > It can be useful for the pinmuxing layer to know which device is > > requesting a GPIO. Add a consumer variant for gpiod_request to > > reach this goal. > > > > GPIO chips managed by pin controllers should provide the new > > request_consumer operation. They can rely on > > gpiochip_generic_request_consumer instead of > > gpiochip_generic_request. > > > > Signed-off-by: Ludovic Desroches <ludovic.desroches@microchip.com> > > I think we need to think over what is a good way to share ownership > of a pin. > > Russell pointed me to a similar problem incidentally and I briefly looked > into it: there are cases when several devices may need to hold the > same pin. > > Can't we just look up the associated gpio_chip from the GPIO range, > and in case the pin is connected between the pin controller and > the GPIO chip, then we allow the gpiochip to also take a > reference? >
It's the probably the way to go, it was Maxime's proposal and Andy seems to agree this solution.
> I.e. in that case you just allow gpio_owner to proceed and take the > pin just like with a non-strict controller. > > Yours, > Linus Walleij
Regards
Ludovic
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