Re: [PATCH 6/6] ARM: shmobile: Armadillo800EVA: Reference DT implementation

[Bastian Hecht <hechtb@gmail.com>]

Hello Laurent,

2013/4/5 Laurent Pinchart <laurent.pinchart@ideasonboard.com>:
> Hi Bastian,
>
> On Thursday 04 April 2013 17:58:40 Bastian Hecht wrote:
>> 2013/4/4 Laurent Pinchart <laurent.pinchart@ideasonboard.com>:
>> > Hi Bastian,
>> >
>> > Thanks for the patch.
>>
>> [snip]
>>
>> >> +     /* Touchscreen */
>> >> +     gpio_request(GPIO_FN_IRQ10,     NULL); /* TP_INT */
>> >
>> > Please, no function GPIO in reference DT implementations.
>>
>> As far as I understood the pinctrl framework, we choose preconfigured
>> settings (in pfc-r8a7740.c) for each device we want to run. We identify
>> these devices by their names, like sh-sci.1. How does that work with devices
>> connected to busses like the I2C controller for which we can't know which
>> GPIOs we need in advance as it is board dependent?
>
> pfc-r8a7740.c defines pin groups and functions. It's then up to board and DT
> files to map the groups and functions they need to devices. The mappings can
> be selected explicitly by drivers, or, for default mappings, automatically by
> the device core. Please see the eva_pinctrl_map array in arch/arm/mach-
> shmobile/board-armadillo800eva.c for mapping examples.

Thanks for the explanation.

>> >> +     gpio_request_one(166, GPIOF_OUT_INIT_HIGH, NULL); /* TP_RST_B */
>> >
>> > The GPIO should be passed to the touchscreen driver through DT. As we have
>> > no GPIO DT bindings for the r8a7740 yet, an option would be to pass it
>> > through platform data (using OF_DEV_AUXDATA).
>>
>> I don't see who would use that data. Does your suggestion include to expand
>> the st1232 driver?
>
> There's two options here. The one I was suggesting indeed involved modifying
> the st1232 driver to handle the reset signal explicitly. The other option
> would be to use pinctrl mappings to configure the GPIO. This isn't possible
> yet with the PFC driver but I'm working on it.

Ah now I'm on track, I guess. So the idea is to be self-contained the
st1232 needs to be supplied with 2 GPIOs and while the IRQ GPIO is
given (indirectly) by the IRQ number, the reset signal is missing. The
"gpio_request(GPIO_FN_IRQ10,     NULL)" is purely board specific to
route the IRQ signal correctly while the reset signal is already muxed
correctly by default and just the output value is changed. So I'll
have a look at the driver and see if I can add the reset GPIO code.

Thanks,

 Bastian

>> So far I see only that the IRQ number is used to set up the IRQ handler. I
>> don't see the connection where the muxing would be done.
>
> --
> Regards,
>
> Laurent Pinchart
>