Re: [PATCH v1 1/2] leds: trigger: gpio: GPIO 0 is valid

Jacek Anaszewski
2019-08-24T16:48:00Z

Hi Andy,

Thank you for the patch.

On 8/21/19 7:17 PM, Andy Shevchenko wrote:
> Allow all valid GPIOs to be used in the driver.
>
> Fixes: 17354bfe8527 ("leds: Add gpio-led trigger")
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> ---
> drivers/leds/trigger/ledtrig-gpio.c | 10 +++++-----
> 1 file changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/leds/trigger/ledtrig-gpio.c b/drivers/leds/trigger/ledtrig-gpio.c
> index 33cc99a1a16a..31f456dd4417 100644
> --- a/drivers/leds/trigger/ledtrig-gpio.c
> +++ b/drivers/leds/trigger/ledtrig-gpio.c
> @@ -131,10 +131,10 @@ static ssize_t gpio_trig_gpio_store(struct device *dev,
> if (gpio_data->gpio == gpio)
> return n;
>
> - if (!gpio) {
> - if (gpio_data->gpio != 0)
> + if (!gpio_is_valid(gpio)) {
> + if (gpio_is_valid(gpio_data->gpio))
> free_irq(gpio_to_irq(gpio_data->gpio), led);
> - gpio_data->gpio = 0;
> + gpio_data->gpio = gpio;

It looks odd to me. I'd just assign invalid constant gpio number
e.g. -1.

Note that we should also do that in gpio_trig_activate(), where
gpio_data->gpio is initialized to 0 by kzalloc(). That later can
have nasty side effect in gpio_trig_gpio_store() when gpio to set
is 0. Then the condition "if (gpio_data->gpio == gpio)" will evaluate
to true and gpio_trig_irq() handler will not be registered.

> return n;
> }
>
> @@ -144,7 +144,7 @@ static ssize_t gpio_trig_gpio_store(struct device *dev,
> if (ret) {
> dev_err(dev, "request_irq failed with error %d\n", ret);
> } else {
> - if (gpio_data->gpio != 0)
> + if (gpio_is_valid(gpio_data->gpio))
> free_irq(gpio_to_irq(gpio_data->gpio), led);
> gpio_data->gpio = gpio;
> /* After changing the GPIO, we need to update the LED. */
> @@ -181,7 +181,7 @@ static void gpio_trig_deactivate(struct led_classdev *led)
> {
> struct gpio_trig_data *gpio_data = led_get_trigger_data(led);
>
> - if (gpio_data->gpio != 0)
> + if (gpio_is_valid(gpio_data->gpio))
> free_irq(gpio_to_irq(gpio_data->gpio), led);
> kfree(gpio_data);
> }
>

--
Best regards,
Jacek Anaszewski