Re: [PATCH 1/7] ARM: shmobile: r8a73a4 dtsi: Add missing "gpio-ranges" to gpio node

[Geert Uytterhoeven <geert@linux-m68k.org>]

Hi Laurent, Linus,

On Tue, Jun 30, 2015 at 11:49 AM, Laurent Pinchart
<laurent.pinchart@ideasonboard.com> wrote:
> On Tuesday 30 June 2015 09:45:21 Geert Uytterhoeven wrote:
>> If a GPIO driver uses gpiochip_add_pin_range() (which is usually the
>> case for GPIO/PFC combos), the GPIO hogging mechanism configured from DT
>> doesn't work:
>>
>>     requesting hog GPIO led1-high (chip r8a73a4_pfc, offset 28) failed
>>
>> The actual error code is -517 == -EPROBE_DEFER.
>>
>> The problem is that PFC+GPIO registration is handled in multiple steps:
>>   1. pinctrl_register(),
>>   2. gpiochip_add(),
>>   3. gpiochip_add_pin_range().
>>
>> Configuration of the hogs is handled in gpiochip_add():
>>
>>     gpiochip_add
>>         of_gpiochip_add
>>             of_gpiochip_scan_hogs
>>                 gpiod_hog
>>                     gpiochip_request_own_desc
>>                         __gpiod_request
>>                             chip->request
>>                                 pinctrl_request_gpio
>>                                     pinctrl_get_device_gpio_range
>>
>> However, at this point the GPIO controller hasn't been added to
>> pinctrldev_list yet, so the range can't be found, and the operation fails
>> with -EPROBE_DEFER.
>>
>> To fix this, add a "gpio-ranges" property to the gpio device node, so
>> the ranges are added by of_gpiochip_add_pin_range(), which is called by
>> of_gpiochip_add() before the call to of_gpiochip_scan_hogs().
>>
>> Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
>
> This looks sane to me, even though referencing the same DT node seems a bit
> dodgy. I'll let Linus comment on that, but for the implementation itself,
>
> Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

Thank you!

Any wise words from Linus?

Thanks again!

>
>> ---
>>  arch/arm/boot/dts/r8a73a4.dtsi | 7 +++++++
>>  1 file changed, 7 insertions(+)
>>
>> diff --git a/arch/arm/boot/dts/r8a73a4.dtsi b/arch/arm/boot/dts/r8a73a4.dtsi
>> index 5090d1a8f652e8be..cb4f7b2798fe23be 100644
>> --- a/arch/arm/boot/dts/r8a73a4.dtsi
>> +++ b/arch/arm/boot/dts/r8a73a4.dtsi
>> @@ -207,6 +207,13 @@
>>               reg = <0 0xe6050000 0 0x9000>;
>>               gpio-controller;
>>               #gpio-cells = <2>;
>> +             gpio-ranges =
>> +                     <&pfc 0 0 31>, <&pfc 32 32 9>,
>> +                     <&pfc 64 64 22>, <&pfc 96 96 31>,
>> +                     <&pfc 128 128 7>, <&pfc 160 160 19>,
>> +                     <&pfc 192 192 31>, <&pfc 224 224 27>,
>> +                     <&pfc 256 256 28>, <&pfc 288 288 21>,
>> +                     <&pfc 320 320 10>;
>>               interrupts-extended =
>>                       <&irqc0  0 0>, <&irqc0  1 0>, <&irqc0  2 0>, <&irqc0  3 0>,
>>                       <&irqc0  4 0>, <&irqc0  5 0>, <&irqc0  6 0>, <&irqc0  7 0>,

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds