On Wed, Oct 23, 2013 at 10:20:59AM +0900, Jingoo Han wrote:
> 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: sta...@vger.kernel.org
> > Signed-off-by: Johan Hovold <jhov...@gmail.com>
> > ---
> > 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'.
Yes, but the cast to int is implicit. Perhaps
return (intensity & 0xffff);
(or just a comment) would make it more clear why the cast is there.
> Also, pwm_channel_readl() returns 'u32'.
Yes, (and only the 16 least-significant bits are used). That and the
fact that the platform-data limits are currently unsigned long (I was
considering fixing this later) was why I preferred keeping all register
value manipulation in u32 and do a single cast at the end.
> 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;
This would actually introduce a new conversion warning (unless you add
parentheses as well) as pwm_duty_min is unsigned long. Same below.
> } 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;
> }
However, if you feel strongly about this, I'll respin the series (a later
patch would likely no longer apply), use u16 and add casts to the two
assignments.
Thanks,
Johan
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
