| Message ID | 1438680424-698-1-git-send-email-mpa@pengutronix.de |
|---|---|
| State | New |
| Headers | show |
On Tue, Aug 4, 2015 at 11:27 AM, Markus Pargmann <mpa@pengutronix.de> wrote: > It can be useful to claim hogged gpios later, for example from > userspace. This allows to set defaults for GPIOs using the hogging > mechanism and override the setup later from userspace or a kernel driver. > > This patch adds a check for hogged gpios to allow requesting them. If > the gpio is not hogged but marked as requested, it still fails with > -EBUSY. > > Signed-off-by: Markus Pargmann <mpa@pengutronix.de> To me it feels like a new DT property "gpio-inital-value" or so need to be defined in addition to the hogging bindings, and that one just sets the GPIO up without setting the FLAG_IS_HOGGED. The mechanism needs to be available to non-DT as well of course, but it could be a first usecase. So instead of: line_b { gpio-initval; gpios = <6 0>; output-low; }; Note: no line-name. And it shouldn't be allowed: we don't know who will use this in the end. Yours, Linus Walleij -- To unsubscribe from this list: send the line "unsubscribe linux-gpio" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hi, On Mon, Aug 10, 2015 at 11:26:49AM +0200, Linus Walleij wrote: > On Tue, Aug 4, 2015 at 11:27 AM, Markus Pargmann <mpa@pengutronix.de> wrote: > > > It can be useful to claim hogged gpios later, for example from > > userspace. This allows to set defaults for GPIOs using the hogging > > mechanism and override the setup later from userspace or a kernel driver. > > > > This patch adds a check for hogged gpios to allow requesting them. If > > the gpio is not hogged but marked as requested, it still fails with > > -EBUSY. > > > > Signed-off-by: Markus Pargmann <mpa@pengutronix.de> > > To me it feels like a new DT property "gpio-inital-value" or so > need to be defined in addition to the hogging bindings, and that > one just sets the GPIO up without setting the FLAG_IS_HOGGED. > > The mechanism needs to be available to non-DT as well > of course, but it could be a first usecase. > > So instead of: > > line_b { > gpio-initval; > gpios = <6 0>; > output-low; > }; > > Note: no line-name. And it shouldn't be allowed: we don't > know who will use this in the end. Sounds good to me. If everyone is okay with this I could go ahead and implement something like this. Best Regards, Markus
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index 926a1507431f..0f1d1f5faf5d 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -830,7 +830,8 @@ static int __gpiod_request(struct gpio_desc *desc, const char *label) * before IRQs are enabled, for non-sleeping (SOC) GPIOs. */ - if (test_and_set_bit(FLAG_REQUESTED, &desc->flags) == 0) { + if (test_and_set_bit(FLAG_REQUESTED, &desc->flags) == 0 || + test_and_clear_bit(FLAG_IS_HOGGED, &desc->flags) == 1) { desc_set_label(desc, label ? : "?"); status = 0; } else {
It can be useful to claim hogged gpios later, for example from userspace. This allows to set defaults for GPIOs using the hogging mechanism and override the setup later from userspace or a kernel driver. This patch adds a check for hogged gpios to allow requesting them. If the gpio is not hogged but marked as requested, it still fails with -EBUSY. Signed-off-by: Markus Pargmann <mpa@pengutronix.de> --- Only change is, that it is separated from the other series now. drivers/gpio/gpiolib.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)