linux-kernel - Re: [PATCH] gpiolib: Allow name duplicates of "" and "NC"

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Message-ID: <CACRpkdZKKetFFm8AanVnzV9SyZhuurLHT_ZTak27-vGEdqVgEw@mail.gmail.com>
Date:   Wed, 16 Dec 2020 13:46:47 +0100
From:   Linus Walleij <linus.walleij@...aro.org>
To:     Bjorn Andersson <bjorn.andersson@...aro.org>
Cc:     Bartosz Golaszewski <bgolaszewski@...libre.com>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        MSM <linux-arm-msm@...r.kernel.org>
Subject: Re: [PATCH] gpiolib: Allow name duplicates of "" and "NC"

On Tue, Dec 15, 2020 at 6:02 PM Bjorn Andersson
<bjorn.andersson@...aro.org> wrote:

> Not all GPIO pins are exposed to the world and this is typically
> described by not giving these lines particular names, commonly "" or
> "NC".
>
> With the recent introduction of '2cd64ae98f35 ("gpiolib: Disallow
> identical line names in the same chip")' any gpiochip with multiple such
> pins will refuse to probe.
>
> Fix this by treating "" and "NC" as "no name specified" in
> gpio_name_to_desc()
>
> Fixes: 2cd64ae98f35 ("gpiolib: Disallow identical line names in the same chip")
> Signed-off-by: Bjorn Andersson <bjorn.andersson@...aro.org>
> ---
>
> The introduction of 2cd64ae98f35 breaks pretty much all Qualcomm boards and
> grepping the DT tree indicates that other vendors will have the same problem.
>
> In addition to this the am335x-* boards will also needs "[NC]", "[ethernet]",
> "[emmc"], "[i2c0]", "[SYSBOOT]" and "[JTAG]" added to this list to allow
> booting v5.11 with the past and present dtb/dts files.

I pushed this patch yesterday that fixes the obvious "(empty string)" problem:
https://lore.kernel.org/linux-gpio/20201215123755.438369-1-linus.walleij@linaro.org/T/#u

But I see this is for device tree line naming only, right?

I think I will conjure a patch allowing identical naming only for
device property naming (like from device tree) but emitting a
warning so that people fix it to something unique moving
forward.

Yours,
Linus Walleij