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SubjectRe: [PATCH 2/8] gpio: zynq: Wakeup gpio controller when it is used as IRQ controller
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On 07. 01. 19 16:42, Thomas Petazzoni wrote:
> Hello,
>
> I am reviving this old thread, because the proposed patch (almost)
> solves the problem I recently reported with the bad interaction of
> runtime PM with the Zynq GPIO driver (see
> https://www.spinics.net/lists/linux-gpio/msg35437.html).
>
> On Mon, 14 Aug 2017 16:33:09 +0200, Michal Simek wrote:
>
>> diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
>> index 9568708a550b..a08a044fa4aa 100644
>> --- a/drivers/gpio/gpiolib.c
>> +++ b/drivers/gpio/gpiolib.c
>> @@ -1647,14 +1647,22 @@ static void gpiochip_irq_unmap(struct irq_domain
>> *d, unsigned int irq)
>> static int gpiochip_irq_reqres(struct irq_data *d)
>> {
>> struct gpio_chip *chip = irq_data_get_irq_chip_data(d);
>> + int ret;
>>
>> if (!try_module_get(chip->gpiodev->owner))
>> return -ENODEV;
>>
>> + ret = pm_runtime_get_sync(chip->parent);
>> + if (ret < 0) {
>> + module_put(chip->gpiodev->owner);
>> + return ret;
>> + }
>> +
>> if (gpiochip_lock_as_irq(chip, d->hwirq)) {
>> chip_err(chip,
>> "unable to lock HW IRQ %lu for IRQ\n",
>> d->hwirq);
>> + pm_runtime_put(chip->parent);
>> module_put(chip->gpiodev->owner);
>> return -EINVAL;
>> }
>> @@ -1666,6 +1674,7 @@ static void gpiochip_irq_relres(struct irq_data *d)
>> struct gpio_chip *chip = irq_data_get_irq_chip_data(d);
>>
>> gpiochip_unlock_as_irq(chip, d->hwirq);
>> + pm_runtime_put(chip->parent);
>> module_put(chip->gpiodev->owner);
>> }
>
> This patch almost solves the problem. It doesn't work as-is, because it
> assumes that runtime PM is used by all GPIO controllers, which is not
> the case. When runtime PM is not enabled, pm_runtime_get_sync() fails
> with -EACCES, and the whole gpiochip_irq_reqres() function aborts.
>
> The following patch works fine in my case (a MMC card detect signal is
> connected to a pin of a PCA GPIO expander over I2C, whose INT# pin is
> itself connected to a GPIO pin of the Zynq SoC).
>
> diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
> index 20887c62fbb3..bd9a81fc8d56 100644
> --- a/drivers/gpio/gpiolib.c
> +++ b/drivers/gpio/gpiolib.c
> @@ -27,6 +27,7 @@
> #include <linux/kfifo.h>
> #include <linux/poll.h>
> #include <linux/timekeeping.h>
> +#include <linux/pm_runtime.h>
> #include <uapi/linux/gpio.h>
>
> #include "gpiolib.h"
> @@ -3540,12 +3541,23 @@ int gpiochip_reqres_irq(struct gpio_chip *chip, unsigned int offset)
> if (!try_module_get(chip->gpiodev->owner))
> return -ENODEV;
>
> + if (pm_runtime_enabled(chip->parent)) {
> + ret = pm_runtime_get_sync(chip->parent);
> + if (ret < 0) {
> + module_put(chip->gpiodev->owner);
> + return ret;
> + }
> + }
> +
> ret = gpiochip_lock_as_irq(chip, offset);
> if (ret) {
> chip_err(chip, "unable to lock HW IRQ %u for IRQ\n", offset);
> + if (pm_runtime_enabled(chip->parent))
> + pm_runtime_put(chip->parent);
> module_put(chip->gpiodev->owner);
> return ret;
> }
> +
> return 0;
> }
> EXPORT_SYMBOL_GPL(gpiochip_reqres_irq);
> @@ -3553,6 +3565,8 @@ EXPORT_SYMBOL_GPL(gpiochip_reqres_irq);
> void gpiochip_relres_irq(struct gpio_chip *chip, unsigned int offset)
> {
> gpiochip_unlock_as_irq(chip, offset);
> + if (pm_runtime_enabled(chip->parent))
> + pm_runtime_put(chip->parent);
> module_put(chip->gpiodev->owner);
> }
> EXPORT_SYMBOL_GPL(gpiochip_relres_irq);
>
> However, I must say that from a design perspective, I am not a big fan
> of this solution. Indeed for the normal GPIO ->request() and ->free()
> hooks, it is currently the GPIO driver itself that is responsible for
> runtime PM get/put, so it would be weird to have the runtime PM get/put
> for the IRQ request/free be done by the GPIO core.
>
> I believe that either the GPIO core should be in charge of the entire
> runtime PM interaction, or it should entirely be the responsibility of
> each GPIO controller driver. Having a mixed solution seems very
> confusing.
>
> Let me know which direction should be taken so that I can submit a
> proper patch to hopefully resolve this issue.

I think it is up to Linus to say which way he wants to go. We found that
way which omap is using.

In connection to this old patch. I think I have tested it later and
wasn't able to replicate it that's why I stop keep track on this.

Thanks,
Michal

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