linux-kernel - [PATCH v2 1/4] gpio: Respect valid

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Message-ID: <e50cf74a587b33cae3133a6b9e0081062f771249.1740745270.git.mazziesaccount@gmail.com>
Date: Fri, 28 Feb 2025 14:35:35 +0200
From: Matti Vaittinen <mazziesaccount@...il.com>
To: Matti Vaittinen <mazziesaccount@...il.com>,
	Matti Vaittinen <matti.vaittinen@...rohmeurope.com>
Cc: Linus Walleij <linus.walleij@...aro.org>,
	Bartosz Golaszewski <brgl@...ev.pl>, linux-gpio@...r.kernel.org,
	linux-kernel@...r.kernel.org, Biju Das <biju.das.jz@...renesas.com>,
	Geert Uytterhoeven <geert@...ux-m68k.org>
Subject: [PATCH v2 1/4] gpio: Respect valid_mask when requesting GPIOs

When GPIOs were requested the validity of GPIOs were checked only when
the GPIO-chip had the request -callback populated. This made using
masked GPIOs possible.

The GPIO chip driver authors may find it difficult to understand the
relation of enforsing the GPIO validity and the 'request' -callback
because the current documentation for the 'request' callback does not
mention this. It only states:

 * @request: optional hook for chip-specific activation, such as
 *      enabling module power and clock; may sleep

The validity of the GPIO line should be checked whether the driver
provides the 'request' callback or not.

Unconditionally check the GPIO validity when GPIO is being requested.

Signed-off-by: Matti Vaittinen <mazziesaccount@...il.com>
---
Revision history:
v1 => v2:
 - New patch (born as a spin-off from the discussion to v1:
   https://lore.kernel.org/all/Z71qphikHPGB0Yuv@mva-rohm/

I'm not sure if this warrants a Fixes -tag.
---
 drivers/gpio/gpiolib.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index fc19df5a64c2..98543d79f69c 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -2326,6 +2326,10 @@ static int gpiod_request_commit(struct gpio_desc *desc, const char *label)
 	if (!guard.gc)
 		return -ENODEV;
 
+	offset = gpio_chip_hwgpio(desc);
+	if (!gpiochip_line_is_valid(guard.gc, offset))
+		return -EINVAL;
+
 	if (test_and_set_bit(FLAG_REQUESTED, &desc->flags))
 		return -EBUSY;
 
@@ -2334,11 +2338,7 @@ static int gpiod_request_commit(struct gpio_desc *desc, const char *label)
 	 */
 
 	if (guard.gc->request) {
-		offset = gpio_chip_hwgpio(desc);
-		if (gpiochip_line_is_valid(guard.gc, offset))
-			ret = guard.gc->request(guard.gc, offset);
-		else
-			ret = -EINVAL;
+		ret = guard.gc->request(guard.gc, offset);
 		if (ret)
 			goto out_clear_bit;
 	}
-- 
2.48.1


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