[Intel-gfx] [PATCH] drm/i915: fix inconsistent brightness after resume

[Jeremiah Mahler]

Jani,

On Mon, Jan 12, 2015 at 12:31:09PM +0200, Jani Nikula wrote:
> On Sat, 10 Jan 2015, Jeremiah Mahler <jmmahler at gmail.com> wrote:
[...]
> 
> I think part of the problem is that the userspace sets brightness to
> minimum before suspend, but apparently does not restore it after
> resume. The dmesg would confirm this. But I guess it doesn't matter,
> since we're pretty much stuck with having to do this anyway.
> 

I did notice it doing this.  There were several calls to *_update_status
as it was entering suspend which set it to the minimum.

I am not familiar with the intricate details of this system but it seems
like there must be a way to fix this.  If the backlight can be powered
off and back on with the correct level it seems like it should be
possible when a suspend/resume is involved.

[...]
> > -	if (panel->backlight.level == 0) {
> > +	if (panel->backlight.level == panel->backlight.min) {
> 
> Perhaps <= instead of == would be safest?
> 
We could do that too in case that corner case ever arises.

[...]

I will fix it up in v2.

-- 
- Jeremiah Mahler