gpio: zynq: properly support runtime PM for GPIO used as interrupts
diff mbox series

Message ID 20190208104046.21817-1-thomas.petazzoni@bootlin.com
State New
Headers show
Series
  • gpio: zynq: properly support runtime PM for GPIO used as interrupts
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Commit Message

Thomas Petazzoni Feb. 8, 2019, 10:40 a.m. UTC
The Zynq GPIO driver currently implements runtime PM by:

 - Enabling runtime PM support in ->probe() and letting the runtime PM
   reference counter drop to zero at the end of ->probe().

 - Increasing the runtime PM reference counter in ->request() and
   decreasing it in ->free().

However, the latter is not sufficient: when a GPIO is used as an
interrupt, ->request() and ->free() are not called. Due to this, the
runtime PM counter remains to zero when the only GPIOs in use are used
as interrupts, causing them to simply not work.

To address this problem, this commit implement the
->irq_request_resources() and ->irq_release_resources() hooks,
ensuring that the runtime PM counter is properly
incremented/decremented. Since we override the default hooks, we keep
the existing behavior by making sure they call gpiochip_reqres_irq() /
gpiochip_relres_irq() respectively.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
---
 drivers/gpio/gpio-zynq.c | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

Comments

Shubhrajyoti Datta Feb. 11, 2019, 1:36 p.m. UTC | #1
Hi Thomas,

Thanks for the patch.

On Fri, Feb 8, 2019 at 4:13 PM Thomas Petazzoni
<thomas.petazzoni@bootlin.com> wrote:
>
> The Zynq GPIO driver currently implements runtime PM by:
>
>  - Enabling runtime PM support in ->probe() and letting the runtime PM
>    reference counter drop to zero at the end of ->probe().
>
>  - Increasing the runtime PM reference counter in ->request() and
>    decreasing it in ->free().
>
> However, the latter is not sufficient: when a GPIO is used as an
> interrupt, ->request() and ->free() are not called. Due to this, the
> runtime PM counter remains to zero when the only GPIOs in use are used
> as interrupts, causing them to simply not work.
>
> To address this problem, this commit implement the
> ->irq_request_resources() and ->irq_release_resources() hooks,
> ensuring that the runtime PM counter is properly
> incremented/decremented. Since we override the default hooks, we keep
> the existing behavior by making sure they call gpiochip_reqres_irq() /
> gpiochip_relres_irq() respectively.
>
> Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
> ---
Reviewed-by: Shubhrajyoti Datta <shubhrajyoti.datta@xilinx.com>
>
Linus Walleij Feb. 13, 2019, 9:37 a.m. UTC | #2
On Fri, Feb 8, 2019 at 11:40 AM Thomas Petazzoni
<thomas.petazzoni@bootlin.com> wrote:

> The Zynq GPIO driver currently implements runtime PM by:
>
>  - Enabling runtime PM support in ->probe() and letting the runtime PM
>    reference counter drop to zero at the end of ->probe().
>
>  - Increasing the runtime PM reference counter in ->request() and
>    decreasing it in ->free().
>
> However, the latter is not sufficient: when a GPIO is used as an
> interrupt, ->request() and ->free() are not called. Due to this, the
> runtime PM counter remains to zero when the only GPIOs in use are used
> as interrupts, causing them to simply not work.
>
> To address this problem, this commit implement the
> ->irq_request_resources() and ->irq_release_resources() hooks,
> ensuring that the runtime PM counter is properly
> incremented/decremented. Since we override the default hooks, we keep
> the existing behavior by making sure they call gpiochip_reqres_irq() /
> gpiochip_relres_irq() respectively.
>
> Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

Patch applied with Shubhrajyoti's review tag.

Yours,
Linus Walleij

Patch
diff mbox series

diff --git a/drivers/gpio/gpio-zynq.c b/drivers/gpio/gpio-zynq.c
index 3f5fcdd5a429..65c0c29ce851 100644
--- a/drivers/gpio/gpio-zynq.c
+++ b/drivers/gpio/gpio-zynq.c
@@ -533,6 +533,26 @@  static int zynq_gpio_set_wake(struct irq_data *data, unsigned int on)
 	return 0;
 }
 
+static int zynq_gpio_irq_reqres(struct irq_data *d)
+{
+	struct gpio_chip *chip = irq_data_get_irq_chip_data(d);
+	int ret;
+
+	ret = pm_runtime_get_sync(chip->parent);
+	if (ret < 0)
+		return ret;
+
+	return gpiochip_reqres_irq(chip, d->hwirq);
+}
+
+static void zynq_gpio_irq_relres(struct irq_data *d)
+{
+	struct gpio_chip *chip = irq_data_get_irq_chip_data(d);
+
+	gpiochip_relres_irq(chip, d->hwirq);
+	pm_runtime_put(chip->parent);
+}
+
 /* irq chip descriptor */
 static struct irq_chip zynq_gpio_level_irqchip = {
 	.name		= DRIVER_NAME,
@@ -542,6 +562,8 @@  static struct irq_chip zynq_gpio_level_irqchip = {
 	.irq_unmask	= zynq_gpio_irq_unmask,
 	.irq_set_type	= zynq_gpio_set_irq_type,
 	.irq_set_wake	= zynq_gpio_set_wake,
+	.irq_request_resources = zynq_gpio_irq_reqres,
+	.irq_release_resources = zynq_gpio_irq_relres,
 	.flags		= IRQCHIP_EOI_THREADED | IRQCHIP_EOI_IF_HANDLED |
 			  IRQCHIP_MASK_ON_SUSPEND,
 };
@@ -554,6 +576,8 @@  static struct irq_chip zynq_gpio_edge_irqchip = {
 	.irq_unmask	= zynq_gpio_irq_unmask,
 	.irq_set_type	= zynq_gpio_set_irq_type,
 	.irq_set_wake	= zynq_gpio_set_wake,
+	.irq_request_resources = zynq_gpio_irq_reqres,
+	.irq_release_resources = zynq_gpio_irq_relres,
 	.flags		= IRQCHIP_MASK_ON_SUSPEND,
 };