| Message ID | 001901cecf8e$21764db0$6462e910$%han@samsung.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
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: stable@vger.kernel.org > > Signed-off-by: Johan Hovold <jhovold@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-fbdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Wednesday, October 23, 2013 5:51 PM, Johan Hovold wrote: > 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: stable@vger.kernel.org > > > Signed-off-by: Johan Hovold <jhovold@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. Thank you for your kind and detailed description. :-) OK, I have no objection on your original patch. Would you re-send these patches with my Acked-by with CC'ing Andrew Morton, Tomi Valkeinen? Then, these patches can be merged through mm-tree. Best regards, Jingoo Han -- To unsubscribe from this list: send the line "unsubscribe linux-fbdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
--- 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,