From: Bartosz Golaszewski <bgolaszewski@baylibre.com>
To: Bjorn Andersson <bjorn.andersson@linaro.org>
Cc: Linus Walleij <linus.walleij@linaro.org>,
linux-gpio <linux-gpio@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
linux-arm-msm@vger.kernel.org
Subject: Re: [PATCH] gpiolib: Allow name duplicates of "" and "NC"
Date: Tue, 15 Dec 2020 18:42:36 +0100 [thread overview]
Message-ID: <CAMpxmJU0XWxiYr716MNGnORJJJ-czuBGWNnFTa5oBTUK4uVheQ@mail.gmail.com> (raw)
In-Reply-To: <20201215170308.2037624-1-bjorn.andersson@linaro.org>
On Tue, Dec 15, 2020 at 6:02 PM Bjorn Andersson
<bjorn.andersson@linaro.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@linaro.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.
>
> drivers/gpio/gpiolib.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
> index b3340ba68471..407ba79ae571 100644
> --- a/drivers/gpio/gpiolib.c
> +++ b/drivers/gpio/gpiolib.c
> @@ -302,7 +302,7 @@ static struct gpio_desc *gpio_name_to_desc(const char * const name)
> struct gpio_device *gdev;
> unsigned long flags;
>
> - if (!name)
> + if (!name || !strcmp(name, "") || !strcmp(name, "NC"))
> return NULL;
>
> spin_lock_irqsave(&gpio_lock, flags);
> --
> 2.29.2
>
I have a bad feeling about this. This opens the door for all kinds of
exceptions: "N/A", "none" etc. Depending on whose boards are getting
broken.
If non-uniqueness of names is needed then let's better revert 2cd64ae98f35.
Bartosz
next prev parent reply other threads:[~2020-12-15 17:43 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-15 17:03 [PATCH] gpiolib: Allow name duplicates of "" and "NC" Bjorn Andersson
2020-12-15 17:42 ` Bartosz Golaszewski [this message]
2020-12-15 17:59 ` Bjorn Andersson
2020-12-16 12:46 ` Linus Walleij
2020-12-16 18:40 ` Bjorn Andersson
2020-12-16 20:50 ` Linus Walleij
2020-12-16 19:53 ` Drew Fustini
2020-12-16 20:38 ` Bjorn Andersson
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