Re: [PATCH 1/9] backlight: atmel-pwm-bl: fix reported brightness

From: Jingoo Han
Date: Tue Oct 22 2013 - 21:21:18 EST


On Wednesday, October 23, 2013 2:27 AM, Johan Hovold wrote:
>
> The driver supports 16-bit brightness values, but the value returned
> from get_brightness was truncated to eight bits.
>
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Johan Hovold <jhovold@xxxxxxxxx>
> ---
> drivers/video/backlight/atmel-pwm-bl.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/video/backlight/atmel-pwm-bl.c b/drivers/video/backlight/atmel-pwm-bl.c
> index 66885fb..8aac273 100644
> --- a/drivers/video/backlight/atmel-pwm-bl.c
> +++ b/drivers/video/backlight/atmel-pwm-bl.c
> @@ -70,7 +70,7 @@ static int atmel_pwm_bl_set_intensity(struct backlight_device *bd)
> static int atmel_pwm_bl_get_intensity(struct backlight_device *bd)
> {
> struct atmel_pwm_bl *pwmbl = bl_get_data(bd);
> - u8 intensity;
> + u32 intensity;
>
> if (pwmbl->pdata->pwm_active_low) {
> intensity = pwm_channel_readl(&pwmbl->pwmc, PWM_CDTY) -
> @@ -80,7 +80,7 @@ static int atmel_pwm_bl_get_intensity(struct backlight_device *bd)
> pwm_channel_readl(&pwmbl->pwmc, PWM_CDTY);
> }
>
> - return intensity;
> + return (u16)intensity;

However, atmel_pwm_bl_get_intensity() should return 'int',
instead of 'u16'. Also, pwm_channel_readl() returns 'u32'.

Then, how about the following?

--- a/drivers/video/backlight/atmel-pwm-bl.c
+++ b/drivers/video/backlight/atmel-pwm-bl.c
@@ -70,17 +70,17 @@ static int atmel_pwm_bl_set_intensity(struct backlight_device *bd)
static int atmel_pwm_bl_get_intensity(struct backlight_device *bd)
{
struct atmel_pwm_bl *pwmbl = bl_get_data(bd);
- u8 intensity;
+ u16 intensity;

if (pwmbl->pdata->pwm_active_low) {
- intensity = pwm_channel_readl(&pwmbl->pwmc, PWM_CDTY) -
+ intensity = (u16) pwm_channel_readl(&pwmbl->pwmc, PWM_CDTY) -
pwmbl->pdata->pwm_duty_min;
} else {
- intensity = pwmbl->pdata->pwm_duty_max -
+ intensity = (u16) pwmbl->pdata->pwm_duty_max -
pwm_channel_readl(&pwmbl->pwmc, PWM_CDTY);
}

- return intensity;
+ return (int)intensity;
}

Best regards,
Jingoo Han

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