From: Andy Shevchenko <andy.shevchenko@gmail.com>
To: Alexander Dahl <ada@thorsis.com>
Cc: "linux-gpio@vger.kernel.org" <linux-gpio@vger.kernel.org>,
Bartosz Golaszewski <bgolaszewski@baylibre.com>,
Linus Walleij <linus.walleij@linaro.org>
Subject: Re: setting gpio-line-names in dts for sama5d2 SoC
Date: Wed, 17 Mar 2021 14:33:58 +0200 [thread overview]
Message-ID: <CAHp75VczovYQB70HVEmDA=xfTBcNuSm2f8x9Mnbj0P0Z4UHRMQ@mail.gmail.com> (raw)
In-Reply-To: <CAHp75Vf05NN0dXUrMSOXBRuYRnQRHO_92itZ3ndOyX1oERWt=g@mail.gmail.com>
+Cc: Bart, Linus
On Wed, Mar 17, 2021 at 1:22 AM Andy Shevchenko
<andy.shevchenko@gmail.com> wrote:
>
>
>
> On Tuesday, March 16, 2021, Alexander Dahl <ada@thorsis.com> wrote:
>>
>> Hei hei,
>>
>> for a Microchip SAMA5D2 SoC based device I try to set gpio-line-names in .dts file like this:
>>
>> 257 &pioA {
>> 258 gpio-line-names = "", /* PA0 */
>> 259 "", /* PA1 */
>> 260 "", /* PA2 */
>> 261 "FOO", /* PA3 */
>> 262 "BAR", /* PA4 */
>> 263 "", /* PA5 */
>>
>> … and so on for all 4 * 32 GPIO Pins. However when calling `gpioinfo` in userspace, I always get this:
>>
>> $ gpioinfo
>> gpiochip0 - 128 lines:
>> line 0: "PA0" unused input active-high
>> line 1: "PA1" unused input active-high
>> line 2: "PA2" unused input active-high
>> line 3: "PA3" unused input active-high
>> line 4: "PA4" unused input active-high
>> line 5: "PA5" unused input active-high
>>
>> … and so on. Those "PA0" line names are set by the pinctrl driver in drivers/pinctrl/pinctrl-at91-pio4.c before calling gpiochip_add_data() and from reading the code in drivers/gpio/gpiolib.c I suspect devprop_gpiochip_set_names() is never called then, so those names in .dts are simply ignored.
>>
>> Those default names from the at91 pio4 pinctrl driver are certainly correct speaking of pin names, but from a userspace point of view it would be better if I could override those from dts, so an application using libgpiod could look for a name like e.g. "VALVE7_EN" without caring to which pin that's actually connected. Can I override those with a currently present kernel? Or is it a problem in either the at91 pio4 driver or the gpiolib core? Or is that no real usecase and should I do it differently?
>
>
> I would like to know the consequences if allow this, but to me it sounds like a bug in the gpiolib.c.
>
>>
>> Greets
>> Alex
>
>
>
> --
> With Best Regards,
> Andy Shevchenko
>
>
--
With Best Regards,
Andy Shevchenko
next prev parent reply other threads:[~2021-03-17 12:35 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-16 13:07 setting gpio-line-names in dts for sama5d2 SoC Alexander Dahl
[not found] ` <CAHp75Vf05NN0dXUrMSOXBRuYRnQRHO_92itZ3ndOyX1oERWt=g@mail.gmail.com>
2021-03-17 12:33 ` Andy Shevchenko [this message]
2021-03-18 9:50 ` Alexander Dahl
2021-03-18 12:40 ` Andy Shevchenko
2021-03-18 13:56 ` Alexander Dahl
2021-03-18 14:59 ` Andy Shevchenko
2021-03-20 11:20 ` Linus Walleij
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