* [PATCH] gpiolib: don't allow OPEN_DRAIN & OPEN_SOURCE flags simultaneously
@ 2017-11-15 15:47 Bartosz Golaszewski
2017-11-29 13:16 ` Linus Walleij
0 siblings, 1 reply; 2+ messages in thread
From: Bartosz Golaszewski @ 2017-11-15 15:47 UTC (permalink / raw)
To: Linus Walleij; +Cc: linux-gpio, linux-kernel, Bartosz Golaszewski
Do not allow OPEN_SOURCE & OPEN_DRAIN flags in a single request. If
the hardware actually supports enabling both at the same time the
electrical result would be disastrous.
Suggested-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
---
There was a misunderstanding as to what the goal of my previous commit
609aaf6a6029 ("gpiolib: don't allow OPEN_DRAIN & OPEN_SOURCE flags for
input") was, which resulted in discovering another thing that needs
fixing. This change was suggested to me by Linus earlier today.
drivers/gpio/gpiolib.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 641a5eb552cb..ec80e0146fd5 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -459,6 +459,15 @@ static int linehandle_create(struct gpio_device *gdev, void __user *ip)
if (lflags & ~GPIOHANDLE_REQUEST_VALID_FLAGS)
return -EINVAL;
+ /*
+ * Do not allow OPEN_SOURCE & OPEN_DRAIN flags in a single request. If
+ * the hardware actually supports enabling both at the same time the
+ * electrical result would be disastrous.
+ */
+ if ((lflags & GPIOHANDLE_REQUEST_OPEN_DRAIN) &&
+ (lflags & GPIOHANDLE_REQUEST_OPEN_SOURCE))
+ return -EINVAL;
+
/* OPEN_DRAIN and OPEN_SOURCE flags only make sense for output mode. */
if (!(lflags & GPIOHANDLE_REQUEST_OUTPUT) &&
((lflags & GPIOHANDLE_REQUEST_OPEN_DRAIN) ||
--
2.13.2
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] gpiolib: don't allow OPEN_DRAIN & OPEN_SOURCE flags simultaneously
2017-11-15 15:47 [PATCH] gpiolib: don't allow OPEN_DRAIN & OPEN_SOURCE flags simultaneously Bartosz Golaszewski
@ 2017-11-29 13:16 ` Linus Walleij
0 siblings, 0 replies; 2+ messages in thread
From: Linus Walleij @ 2017-11-29 13:16 UTC (permalink / raw)
To: Bartosz Golaszewski; +Cc: linux-gpio, linux-kernel
On Wed, Nov 15, 2017 at 4:47 PM, Bartosz Golaszewski <brgl@bgdev.pl> wrote:
> Do not allow OPEN_SOURCE & OPEN_DRAIN flags in a single request. If
> the hardware actually supports enabling both at the same time the
> electrical result would be disastrous.
>
> Suggested-by: Linus Walleij <linus.walleij@linaro.org>
> Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
> ---
> There was a misunderstanding as to what the goal of my previous commit
> 609aaf6a6029 ("gpiolib: don't allow OPEN_DRAIN & OPEN_SOURCE flags for
> input") was, which resulted in discovering another thing that needs
> fixing. This change was suggested to me by Linus earlier today.
Awesome, thanks.
Patch applied.
I wonder if we should even put some swear words into dmesg
for this.
Yours,
Linus Walleij
^ permalink raw reply [flat|nested] 2+ messages in thread
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