Re: [PATCH v4 3/9] gpiolib: acpi: Take into account debounce settings

[Hans de Goede <hdegoede@redhat.com>]

Hi,

On 11/6/20 8:22 PM, Andy Shevchenko wrote:
> We didn't take into account the debounce settings supplied by ACPI.
> This change is targeting the mentioned gap.
> 
> Reported-by: Coiby Xu <coiby.xu@gmail.com>
> Cc: Hans de Goede <hdegoede@redhat.com>
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> Acked-by: Linus Walleij <linus.walleij@linaro.org>

I added an older version of this (which only modified acpi_dev_gpio_irq_get())
for testing and when booting a kernel with that version applied to it,
on a Cherry Trail device I noticed that a whole bunch of devices where no
longer seen by the kernel because of acpi_dev_gpio_irq_get() returning
errors now (-ENOTSUPP).

Quoting from the gpiod_set_debounce docs:

/**
 * gpiod_set_debounce - sets @debounce time for a GPIO
 * @desc: descriptor of the GPIO for which to set debounce time
 * @debounce: debounce time in microseconds
 *
 * Returns:
 * 0 on success, %-ENOTSUPP if the controller doesn't support setting the
 * debounce time.
 */

This is expected on GPIO chips where setting the debounce time
is not supported. So the error handling should be modified to
ignore -ENOTSUPP errors here.

This certainly MUST NOT be merged as is because it breaks a lot
of things as is.

Regards,

Hans




> ---
>  drivers/gpio/gpiolib-acpi.c | 18 ++++++++++++++++++
>  drivers/gpio/gpiolib-acpi.h |  2 ++
>  2 files changed, 20 insertions(+)
> 
> diff --git a/drivers/gpio/gpiolib-acpi.c b/drivers/gpio/gpiolib-acpi.c
> index c127b410a7a2..b4a0decfeac2 100644
> --- a/drivers/gpio/gpiolib-acpi.c
> +++ b/drivers/gpio/gpiolib-acpi.c
> @@ -299,6 +299,10 @@ static acpi_status acpi_gpiochip_alloc_event(struct acpi_resource *ares,
>  		return AE_OK;
>  	}
>  
> +	ret = gpiod_set_debounce(desc, agpio->debounce_timeout);
> +	if (ret)
> +		goto fail_free_desc;
> +
>  	ret = gpiochip_lock_as_irq(chip, pin);
>  	if (ret) {
>  		dev_err(chip->parent,
> @@ -664,6 +668,7 @@ static int acpi_populate_gpio_lookup(struct acpi_resource *ares, void *data)
>  		lookup->desc = acpi_get_gpiod(agpio->resource_source.string_ptr,
>  					      agpio->pin_table[pin_index]);
>  		lookup->info.pin_config = agpio->pin_config;
> +		lookup->info.debounce = agpio->debounce_timeout;
>  		lookup->info.gpioint = gpioint;
>  
>  		/*
> @@ -961,6 +966,10 @@ int acpi_dev_gpio_irq_get(struct acpi_device *adev, int index)
>  			if (ret < 0)
>  				return ret;
>  
> +			ret = gpiod_set_debounce(desc, info.debounce);
> +			if (ret)
> +				return ret;
> +
>  			irq_flags = acpi_dev_get_irq_type(info.triggering,
>  							  info.polarity);
>  
> @@ -1048,6 +1057,7 @@ acpi_gpio_adr_space_handler(u32 function, acpi_physical_address address,
>  		if (!found) {
>  			enum gpiod_flags flags = acpi_gpio_to_gpiod_flags(agpio);
>  			const char *label = "ACPI:OpRegion";
> +			int ret;
>  
>  			desc = gpiochip_request_own_desc(chip, pin, label,
>  							 GPIO_ACTIVE_HIGH,
> @@ -1058,6 +1068,14 @@ acpi_gpio_adr_space_handler(u32 function, acpi_physical_address address,
>  				goto out;
>  			}
>  
> +			ret = gpiod_set_debounce(desc, agpio->debounce_timeout);
> +			if (ret) {
> +				status = AE_ERROR;
> +				gpiochip_free_own_desc(desc);
> +				mutex_unlock(&achip->conn_lock);
> +				goto out;
> +			}
> +
>  			conn = kzalloc(sizeof(*conn), GFP_KERNEL);
>  			if (!conn) {
>  				status = AE_NO_MEMORY;
> diff --git a/drivers/gpio/gpiolib-acpi.h b/drivers/gpio/gpiolib-acpi.h
> index 1c6d65cf0629..e2edb632b2cc 100644
> --- a/drivers/gpio/gpiolib-acpi.h
> +++ b/drivers/gpio/gpiolib-acpi.h
> @@ -18,6 +18,7 @@ struct acpi_device;
>   * @pin_config: pin bias as provided by ACPI
>   * @polarity: interrupt polarity as provided by ACPI
>   * @triggering: triggering type as provided by ACPI
> + * @debounce: debounce timeout as provided by ACPI
>   * @quirks: Linux specific quirks as provided by struct acpi_gpio_mapping
>   */
>  struct acpi_gpio_info {
> @@ -27,6 +28,7 @@ struct acpi_gpio_info {
>  	int pin_config;
>  	int polarity;
>  	int triggering;
> +	unsigned int debounce;
>  	unsigned int quirks;
>  };
>  
>