| Message ID | 20201204164739.781812-2-maz@kernel.org |
|---|---|
| State | New |
| Headers | show |
| Series | [1/4] gpiolib: cdev: Flag invalid GPIOs as used | expand |
On Fri, Dec 04, 2020 at 04:47:36PM +0000, Marc Zyngier wrote: > 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; So this is somewhat separate from the rest of the series in case it applies also to gpio chips with reserved ranges (e.g. "gpio-reserved-ranges" devicetree property). Are they currently reported as available? Looks like this will work well also for USB gpio controllers with static muxing configured in EEPROM, especially as that is how we already report pins reported as unavailable by pinctrl (i.e. ok_for_pinctrl). Johan
On 2020-12-07 14:16, Johan Hovold wrote: > On Fri, Dec 04, 2020 at 04:47:36PM +0000, Marc Zyngier wrote: >> 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; > > So this is somewhat separate from the rest of the series in case it > applies also to gpio chips with reserved ranges (e.g. > "gpio-reserved-ranges" devicetree property). Are they currently > reported > as available? I don't have any HW that uses this, but gpiolib-of.c makes use of it to expose the valid GPIO range. I expect these systems suffer from the same issue. > Looks like this will work well also for USB gpio controllers with > static > muxing configured in EEPROM, especially as that is how we already > report > pins reported as unavailable by pinctrl (i.e. ok_for_pinctrl). Thanks, M. -- Jazz is not dead. It just smells funny...
On Fri, Dec 4, 2020 at 5:47 PM Marc Zyngier <maz@kernel.org> wrote: > 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> This makes sense, so patch applied (unless Bartosz tells me otherwise, then I'll pull it out again). Yours, Linus Walleij
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;
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(+)