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@xxxxxxxxxx> > --- > 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
