Re: [periperi] How to set default GPIO pin ?

Re: [periperi] How to set default GPIO pin ?

[Linus Walleij]

On Wed, Sep 10, 2014 at 10:55 AM, Laurent Pinchart
<laurent.pinchart@ideasonboard.com> wrote:
> On Sunday 31 August 2014 22:08:52 Kuninori Morimoto wrote:
>>
>> I know we can use "defalt" PFC settings on DT.
>> But, how to use "defalt" GPIO pin settings on DT ?
>>
>> We would like to use GPIO 7-17 as Low output,
>> and do nothing after boot.
>
> From a DT point of view I believe this is supposed to be done by specifying
> the output-low or output-high properties in the pinctrl configuration node.
> However, these properties are not supported by the PFC driver, and there's no
> easy way for the PFC driver to configure GPIOs handled by a different driver
> such as the gpio-rcar driver for instance.
>
> Linus, do you have any hindsight on how this should be implemented ?

I have suggested adding GPIO hogs, so that a GPIO node can specify
that some GPIO's specified on the local ship be hogged high or
low at probe. Generic DT bindings and generic code in gpiolib.c.

gpios-hog-high = <....>;
gpios-hog-low = <....>;

Yours,
Linus Walleij

Re: [periperi] How to set default GPIO pin ?

[Laurent Pinchart]

Hi Linus and Morimoto-san,

On Tuesday 23 September 2014 17:06:28 Linus Walleij wrote:
> On Wed, Sep 10, 2014 at 10:55 AM, Laurent Pinchart wrote:
> > On Sunday 31 August 2014 22:08:52 Kuninori Morimoto wrote:
> >> I know we can use "defalt" PFC settings on DT.
> >> But, how to use "defalt" GPIO pin settings on DT ?
> >> 
> >> We would like to use GPIO 7-17 as Low output,
> >> and do nothing after boot.
> > 
> > From a DT point of view I believe this is supposed to be done by
> > specifying the output-low or output-high properties in the pinctrl
> > configuration node. However, these properties are not supported by the PFC
> > driver, and there's no easy way for the PFC driver to configure GPIOs
> > handled by a different driver such as the gpio-rcar driver for instance.
> > 
> > Linus, do you have any hindsight on how this should be implemented ?
> 
> I have suggested adding GPIO hogs, so that a GPIO node can specify
> that some GPIO's specified on the local ship be hogged high or
> low at probe. Generic DT bindings and generic code in gpiolib.c.
> 
> gpios-hog-high = <....>;
> gpios-hog-low = <....>;

How about just a gpios-hog property, with a list of gpio specifiers + flags ? 
That's bikeshedding I suppose.

Morimoto-san, would you like to implement that ? :-)

-- 
Regards,

Laurent Pinchart

Re: [periperi] How to set default GPIO pin ?

[Kuninori Morimoto]

Hi Laurent, Linus

> > I have suggested adding GPIO hogs, so that a GPIO node can specify
> > that some GPIO's specified on the local ship be hogged high or
> > low at probe. Generic DT bindings and generic code in gpiolib.c.
> > 
> > gpios-hog-high = <....>;
> > gpios-hog-low = <....>;
> 
> How about just a gpios-hog property, with a list of gpio specifiers + flags ? 
> That's bikeshedding I suppose.
> 
> Morimoto-san, would you like to implement that ? :-)

Thank you for your help
OK, I try to implement this method (when I have time :)
Thank you

Best regards
---
Kuninori Morimoto

Re: [periperi] How to set default GPIO pin ?

[Linus Walleij]

On Sun, Sep 28, 2014 at 11:25 PM, Laurent Pinchart
<laurent.pinchart@ideasonboard.com> wrote:
> Hi Linus and Morimoto-san,
>
> On Tuesday 23 September 2014 17:06:28 Linus Walleij wrote:
>> On Wed, Sep 10, 2014 at 10:55 AM, Laurent Pinchart wrote:
>> > On Sunday 31 August 2014 22:08:52 Kuninori Morimoto wrote:
>> >> I know we can use "defalt" PFC settings on DT.
>> >> But, how to use "defalt" GPIO pin settings on DT ?
>> >>
>> >> We would like to use GPIO 7-17 as Low output,
>> >> and do nothing after boot.
>> >
>> > From a DT point of view I believe this is supposed to be done by
>> > specifying the output-low or output-high properties in the pinctrl
>> > configuration node. However, these properties are not supported by the PFC
>> > driver, and there's no easy way for the PFC driver to configure GPIOs
>> > handled by a different driver such as the gpio-rcar driver for instance.
>> >
>> > Linus, do you have any hindsight on how this should be implemented ?
>>
>> I have suggested adding GPIO hogs, so that a GPIO node can specify
>> that some GPIO's specified on the local ship be hogged high or
>> low at probe. Generic DT bindings and generic code in gpiolib.c.
>>
>> gpios-hog-high = <....>;
>> gpios-hog-low = <....>;
>
> How about just a gpios-hog property, with a list of gpio specifiers + flags ?
> That's bikeshedding I suppose.
>
> Morimoto-san, would you like to implement that ? :-)

There was a proposed implementation from Boris BREZILLON, but I was
unhappy with parts of it, however check it and see my comments on
the patch set:
"[RFC PATCH] gpio: add GPIO hogging mechanism"

Yours,
Linus Walleij