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SubjectRE: [PATCH] s3c/s3c24xx: arm: leds: Make s3c24xx LEDS driver use gpiolib
Denis Kuzmenko wrote at Thursday, November 17, 2011 1:47 PM:
> Make s3c24xx LEDS driver use gpiolib.

Structurally this looks fine to me, but I made some slightly nit-picky
comments below.

> diff --git a/drivers/leds/leds-s3c24xx.c b/drivers/leds/leds-s3c24xx.c

> static void s3c24xx_led_set(struct led_classdev *led_cdev,
> - enum led_brightness value)
> + enum led_brightness value)

Seems unnecessary, but is probably fine.

> {
> struct s3c24xx_gpio_led *led = to_gpio(led_cdev);
> struct s3c24xx_led_platdata *pd = led->pdata;
>
> - /* there will be a short delay between setting the output and
> - * going from output to input when using tristate. */
> -
> - s3c2410_gpio_setpin(pd->gpio, (value ? 1 : 0) ^
> - (pd->flags & S3C24XX_LEDF_ACTLOW));
> -
> - if (pd->flags & S3C24XX_LEDF_TRISTATE)
> - s3c2410_gpio_cfgpin(pd->gpio,
> - value ? S3C2410_GPIO_OUTPUT : S3C2410_GPIO_INPUT);
> + /*
> + * ensure value is 0 or 1 to use it with bitwise XOR (^)
> + * (only 100% brightness is supported)
> + */
> + value = value ? 1 : 0;
> +
> + if (pd->flags & S3C24XX_LEDF_TRISTATE) {
> + if (value) {
> + /* invert value if S3C24XX_LEDF_ACTLOW is set */
> + value = (pd->flags & S3C24XX_LEDF_ACTLOW) ^ value;
> + gpio_direction_output(pd->gpio, value);
> + } else {
> + gpio_direction_input(pd->gpio);
> + }
> + } else {
> + /* invert value if S3C24XX_LEDF_ACTLOW is set */
> + value = (pd->flags & S3C24XX_LEDF_ACTLOW) ^ value;
> + gpio_set_value(pd->gpio, value);
> + }

I'd be tempted to simplify the new code a little:

/* invert value if S3C24XX_LEDF_ACTLOW is set */
value = !!(pd->flags & S3C24XX_LEDF_ACTLOW) ^ !!value;

if (pd->flags & S3C24XX_LEDF_TRISTATE) {
if (value)
gpio_direction_output(pd->gpio, value);
else
gpio_direction_input(pd->gpio);
} else {
gpio_set_value(pd->gpio, value);
}

> @@ -76,7 +88,8 @@ static int s3c24xx_led_probe(struct platform_device *dev)
> led = kzalloc(sizeof(struct s3c24xx_gpio_led), GFP_KERNEL);
> if (led == NULL) {
> dev_err(&dev->dev, "No memory for device\n");
> - return -ENOMEM;
> + ret = -ENOMEM;
> + goto err_kzalloc;
> }

That works fine, but isn't strictly necessary; no previous allocations
have been made here that need to be undone.

> @@ -91,12 +104,15 @@ static int s3c24xx_led_probe(struct platform_device
> *dev)
> /* no point in having a pull-up if we are always driving */
>
> if (pdata->flags & S3C24XX_LEDF_TRISTATE) {
> - s3c2410_gpio_setpin(pdata->gpio, 0);
> - s3c2410_gpio_cfgpin(pdata->gpio, S3C2410_GPIO_INPUT);
> + ret = gpio_request_one(pdata->gpio, GPIOF_IN, pdata->name);
> } else {
> - s3c2410_gpio_pullup(pdata->gpio, 0);
> - s3c2410_gpio_setpin(pdata->gpio, 0);
> - s3c2410_gpio_cfgpin(pdata->gpio, S3C2410_GPIO_OUTPUT);
> + ret = gpio_request_one(pdata->gpio, GPIOF_OUT_INIT_LOW,
> + pdata->name);
> + s3c_gpio_setpull(pdata->gpio, S3C_GPIO_PULL_NONE);
> + }

I always prefer not to duplicate function calls, but rather to calculate
the differing data (either directly in the call, or into a temporary
variable first), so:

ret = gpio_request_one(pdata->gpio,
(pdata->flags & S3C24XX_LEDF_TRISTATE) ?
GPIOF_IN : GPIOF_OUT_INIT_LOW,
pdata->name);

if (!(pdata->flags & S3C24XX_LEDF_TRISTATE))
s3c_gpio_setpull(pdata->gpio, S3C_GPIO_PULL_NONE);


> + if (ret < 0) {
> + dev_err(&dev->dev, "gpio_request failed\n");
> + goto err_gpio_request;
> }

You should probably move that error check right after calling
gpio_request_one()

--
nvpublic



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