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From: Marc Zyngier <maz@kernel.org>
To: linux-usb@vger.kernel.org, linux-gpio@vger.kernel.org,
	linux-kernel@vger.kernel.org
Cc: Linus Walleij <linus.walleij@linaro.org>,
	Bartosz Golaszewski <bgolaszewski@baylibre.com>,
	Johan Hovold <johan@kernel.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	kernel-team@android.com
Subject: [PATCH 1/4] gpiolib: cdev: Flag invalid GPIOs as used
Date: Fri,  4 Dec 2020 16:47:36 +0000	[thread overview]
Message-ID: <20201204164739.781812-2-maz@kernel.org> (raw)
In-Reply-To: <20201204164739.781812-1-maz@kernel.org>

When reporting the state of a GPIO to userspace, we never check
for the actual validity of the line, meaning we report invalid
lines as being usable. A subsequent request will fail though,
which is an inconsistent behaviour from a userspace perspective.

Instead, let's check for the validity of the line and report it
as used if it is invalid. This allows a tool such as gpioinfo
to report something sensible:

gpiochip3 - 4 lines:
	line   0:      unnamed       unused   input  active-high
	line   1:      unnamed       kernel   input  active-high [used]
	line   2:      unnamed       kernel   input  active-high [used]
	line   3:      unnamed       unused   input  active-high

In this example, lines 1 and 2 are invalid, and cannot be used by
userspace.

Signed-off-by: Marc Zyngier <maz@kernel.org>
---
 drivers/gpio/gpiolib-cdev.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/gpio/gpiolib-cdev.c b/drivers/gpio/gpiolib-cdev.c
index e9faeaf65d14..a0fcb4ccaa02 100644
--- a/drivers/gpio/gpiolib-cdev.c
+++ b/drivers/gpio/gpiolib-cdev.c
@@ -1910,6 +1910,7 @@ static void gpio_desc_to_lineinfo(struct gpio_desc *desc,
 	    test_bit(FLAG_USED_AS_IRQ, &desc->flags) ||
 	    test_bit(FLAG_EXPORT, &desc->flags) ||
 	    test_bit(FLAG_SYSFS, &desc->flags) ||
+	    !gpiochip_line_is_valid(gc, info->offset) ||
 	    !ok_for_pinctrl)
 		info->flags |= GPIO_V2_LINE_FLAG_USED;
 
-- 
2.28.0


  reply	other threads:[~2020-12-04 16:48 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-04 16:47 [PATCH 0/4] USB: ftdio_sio: GPIO validity fixes Marc Zyngier
2020-12-04 16:47 ` Marc Zyngier [this message]
2020-12-07 14:16   ` [PATCH 1/4] gpiolib: cdev: Flag invalid GPIOs as used Johan Hovold
2020-12-07 14:59     ` Marc Zyngier
2020-12-09  9:25   ` Linus Walleij
2020-12-04 16:47 ` [PATCH 2/4] USB: serial: ftdi_sio: Report the valid GPIO lines to gpiolib Marc Zyngier
2020-12-09  9:28   ` Linus Walleij
2020-12-04 16:47 ` [PATCH 3/4] USB: serial: ftdi_sio: Log the CBUS GPIO validity Marc Zyngier
2020-12-07 14:29   ` Johan Hovold
2020-12-07 15:00     ` Marc Zyngier
2020-12-07 15:19       ` Johan Hovold
2020-12-09  9:35         ` Linus Walleij
2020-12-09 17:05           ` Johan Hovold
2020-12-09 17:39             ` Johan Hovold
2020-12-04 16:47 ` [PATCH 4/4] USB: serial: ftdi_sio: Drop GPIO line checking dead code Marc Zyngier
2020-12-07  9:55 ` [PATCH 0/4] USB: ftdio_sio: GPIO validity fixes Andy Shevchenko
2020-12-07 14:01 ` Johan Hovold
2020-12-07 14:41   ` Marc Zyngier
2020-12-07 15:08     ` Johan Hovold
2020-12-07 15:34       ` Marc Zyngier
2020-12-07 15:49         ` Johan Hovold
2020-12-09  9:20           ` Linus Walleij
2020-12-09 15:42             ` Johan Hovold

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