[Intel-gfx] [PATCH] drm/i915: fix backlight invert for non-zero minimum brightness

[Jani Nikula]

On Wed, 31 May 2017, Daniel Vetter <daniel at ffwll.ch> wrote:
> On Wed, May 31, 2017 at 11:33:55AM +0300, Jani Nikula wrote:
>> When we started following the backlight minimum brightness in
>> 6dda730e55f4 ("drm/i915: respect the VBT minimum backlight brightness")
>> we overlooked the brightness invert quirk. Even if we invert the
>> brightness, we need to take the min limit into account. We probably
>> missed this because the invert has only been required on gen4 for proper
>> operation.
>> 
>> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=101127
>> Fixes: 6dda730e55f4 ("drm/i915: respect the VBT minimum backlight brightness")
>> Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
>> Cc: <stable at vger.kernel.org> # v3.17+
>
> Not sure the cc: stable is justified, but makes sense otherwise
>
> Reviewed-by: Daniel Vetter <daniel.vetter at ffwll.ch>

Had forgotten about this, pushed now, without cc: stable.

Thanks for the review.

BR,
Jani.


>
>> Signed-off-by: Jani Nikula <jani.nikula at intel.com>
>> ---
>>  drivers/gpu/drm/i915/intel_panel.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>> 
>> diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c
>> index cb50c527401f..bcde9f34527a 100644
>> --- a/drivers/gpu/drm/i915/intel_panel.c
>> +++ b/drivers/gpu/drm/i915/intel_panel.c
>> @@ -469,7 +469,7 @@ static u32 intel_panel_compute_brightness(struct intel_connector *connector,
>>  
>>  	if (i915.invert_brightness > 0 ||
>>  	    dev_priv->quirks & QUIRK_INVERT_BRIGHTNESS) {
>> -		return panel->backlight.max - val;
>> +		return panel->backlight.max - val + panel->backlight.min;
>>  	}
>>  
>>  	return val;
>> -- 
>> 2.11.0
>> 

-- 
Jani Nikula, Intel Open Source Technology Center