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SubjectRe: [PATCH 1/2] ledtrig-gpio: Request user input pin as GPIO
Cc: += linux-gpio@vger.kernel.org

On Thu, May 16, 2019 at 02:42:08PM -0700, Kun Yi wrote:
> The ledtrig-gpio logic assumes the input pin can be directly converted
> to IRQ using gpio_to_irq. This is problematic since there is no
> guarantee on the pinmux function nor the direction of the pin. Request
> the pin as an input GPIO before requesting it as an IRQ.

When reading this I thought the driver requested the gpio only after
converting to an irq. But in fact it didn't request and set the
direction at all.

> Tested: a free pin can be correctly requested as GPIO

This doesn't belong into the signed-off-area.

> Signed-off-by: Kun Yi <kunyi@google.com>
> Change-Id: I657e3e108552612506775cc348a8b4b35d40cac5

This doesn't belong into the linux history either.

> ---
> drivers/leds/trigger/ledtrig-gpio.c | 31 +++++++++++++++++++++++------
> 1 file changed, 25 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/leds/trigger/ledtrig-gpio.c b/drivers/leds/trigger/ledtrig-gpio.c
> index ed0db8ed825f..f6d50e031492 100644
> --- a/drivers/leds/trigger/ledtrig-gpio.c
> +++ b/drivers/leds/trigger/ledtrig-gpio.c
> @@ -117,6 +117,16 @@ static ssize_t gpio_trig_gpio_show(struct device *dev,
> return sprintf(buf, "%u\n", gpio_data->gpio);
> }
>
> +static inline void free_used_gpio_if_valid(unsigned int gpio,
> + struct led_classdev *led)

Please stick to the function prefix used in this driver. I'd call this
function gpio_trig_free_gpio and not put "if_valid" into the name.

> +{
> + if (gpio == 0)
> + return;
> +
> + free_irq(gpio_to_irq(gpio), led);
> + gpio_free(gpio);
> +}
> +
> static ssize_t gpio_trig_gpio_store(struct device *dev,
> struct device_attribute *attr, const char *buf, size_t n)
> {
> @@ -135,20 +145,30 @@ static ssize_t gpio_trig_gpio_store(struct device *dev,
> return n;
>
> if (!gpio) {
> - if (gpio_data->gpio != 0)
> - free_irq(gpio_to_irq(gpio_data->gpio), led);
> + free_used_gpio_if_valid(gpio_data->gpio, led);
> gpio_data->gpio = 0;
> return n;
> }
>
> + ret = gpio_request(gpio, "ledtrig-gpio");
> + if (ret) {
> + dev_err(dev, "gpio_request failed with error %d\n", ret);
> + return ret;
> + }
> +
> + ret = gpio_direction_input(gpio);
> + if (ret) {
> + dev_err(dev, "gpio_direction_input failed with err %d\n", ret);
> + return ret;
> + }

Please use gpio_request_one which implements both gpio_request() and
gpio_direction_*(). This also fixes the missing gpio_free() in the error
path of gpio_direction_input().

> +
> ret = request_threaded_irq(gpio_to_irq(gpio), NULL, gpio_trig_irq,
> IRQF_ONESHOT | IRQF_SHARED | IRQF_TRIGGER_RISING
> | IRQF_TRIGGER_FALLING, "ledtrig-gpio", led);
> if (ret) {
> dev_err(dev, "request_irq failed with error %d\n", ret);
> } else {
> - if (gpio_data->gpio != 0)
> - free_irq(gpio_to_irq(gpio_data->gpio), led);
> + free_used_gpio_if_valid(gpio_data->gpio, led);
> gpio_data->gpio = gpio;
> /* After changing the GPIO, we need to update the LED. */
> gpio_trig_irq(0, led);
> @@ -184,8 +204,7 @@ 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)
> - free_irq(gpio_to_irq(gpio_data->gpio), led);
> + free_used_gpio_if_valid(gpio_data->gpio, led);
> kfree(gpio_data);
> }
>

Best regards
Uwe

--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | http://www.pengutronix.de/ |

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