Messages in this thread |  | | From | Andy Shevchenko <> | Date | Fri, 26 Jan 2018 19:13:32 +0200 | Subject | Re: [RFC PATCH 2/2] gpio: provide a consumer when requesting a gpio |
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On Fri, Jan 26, 2018 at 9:32 AM, Ludovic Desroches <ludovic.desroches@microchip.com> wrote: > On Wed, Jan 24, 2018 at 05:42:15PM +0200, Andy Shevchenko wrote: >> On Wed, Jan 24, 2018 at 3:07 PM, Ludovic Desroches >> <ludovic.desroches@microchip.com> wrote: >> > On Thu, Jan 18, 2018 at 04:22:28PM +0100, Ludovic Desroches wrote: >> >> On Thu, Jan 18, 2018 at 11:30:00AM +0100, Linus Walleij wrote:
>> >> > 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? >> >> How do you find my proposal about introducing ownership level (not >> requested yet; exclusive; shared)?
> Yes but I don't see how I can fix my issue with these levels. In my > case, I need an exclusive ownership at device level not at pin level. In > reality, it is at pin level but I am in this situation because my pin > controler was introduced as non strict and also because I need to set > the configuration of the pin which is going to be used as a GPIO. > > If the ownership is exclusive, pinmuxing coming from pinctrl-default > will be accepted but the GPIO request will fail even if it comes from the > same device.
The problem here is to declare a right consumer of the resource.
My understanding that consumer at the end is device or device(s):
none: resource is free to acquire exclusive: certain device has access to the resource (pin) shared: several devices may access to the resource
In both cases couple of caveats: - power management has a special access level to the resource on behalf of the owner(s) - it can have some flags, like 'locked', which means no more owners can be changed / added, but still possible to free resource by all owners to go to state 'none'
> If the ownership is shared then, pinmuxing coming from pinctrl-default > will be accepted but a GPIO request from another device will be accepted > too. > > Both situations are incorrect in my case.
Yes, since the ownership design is based on subsystem rather consumer device.
> Let me know if I have not well understood your proposal. My concern is > to get out of this situation without breaking current DTs.
See above, hope it clarifies a bit.
-- With Best Regards, Andy Shevchenko
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