Re: [PATCH] drm/i915: Update PSR on resume.

[Daniel Vetter <daniel@ffwll.ch>]

On Wed, Jun 04, 2014 at 12:17:14PM -0700, Rodrigo Vivi wrote:
> On Wed, May 28, 2014 at 5:57 AM, Daniel Vetter <daniel@ffwll.ch> wrote:
> 
> > On Tue, May 27, 2014 at 04:50:14PM -0700, Rodrigo Vivi wrote:
> > > Some registers set during setup might not be persistent after
> > suspend/resume.
> > > This was causing bugs for some people that was unable to get PSR entry
> > state
> > > after resume cycle.
> > >
> > > v2: Adding some comments and better commit message explaining why this
> > is needed.
> > >
> > > Signed-off-by: Rodrigo Vivi <rodrigo.vivi@gmail.com>
> > > ---
> > >  drivers/gpu/drm/i915/i915_suspend.c | 6 ++++++
> > >  1 file changed, 6 insertions(+)
> > >
> > > diff --git a/drivers/gpu/drm/i915/i915_suspend.c
> > b/drivers/gpu/drm/i915/i915_suspend.c
> > > index 56785e8..1923708 100644
> > > --- a/drivers/gpu/drm/i915/i915_suspend.c
> > > +++ b/drivers/gpu/drm/i915/i915_suspend.c
> > > @@ -288,6 +288,12 @@ static void i915_restore_display(struct drm_device
> > *dev)
> > >               I915_WRITE(PP_CONTROL, dev_priv->regfile.savePP_CONTROL);
> > >       }
> > >
> > > +     /* Forcing a full init sequence after resume to make sure all
> > > +     * registers are properly set. Some might not be persistent after
> > > +     * suspend/resume cycle. */
> > > +     dev_priv->psr.setup_done = false;
> > > +     intel_edp_psr_update(dev);
> >
> > No, crtc_enable should take care of this. There's more places (like after
> > runtime pm) where the hw has potentially lost all register contents, so
> > crtc_enabl is the right place for this.
> > -Daniel
> >
> 
> crtc_enable takes care of the update, but not the setup part that is done
> only once...
> I do believe that only the setup_done = false is really needed here, but
> doesn't heart to trigger the update right here
> and fixes the bug...

restore_display hurts. If there's some setup we need to do, we _really_
need to do it in crtc_enable. Splattering setup code all over the code is
one of the prime sources of bugs we have wrt rpm, s/r and driver load.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch