[Intel-gfx] [PATCH] drm/i915: don't force VDD on when shutting down a panel

[Jesse Barnes]

On Wed, 4 Dec 2013 18:24:56 -0200
Paulo Zanoni <przanoni at gmail.com> wrote:

> 2013/12/4 Jesse Barnes <jbarnes at virtuousgeek.org>:
> > This causes trouble on some VLV systems, and generally costs power
> > elsewhere.
> >
> > If this ends up causing trouble, it could just mean we need to get rid
> > of VDD force enable everywhere, and move to a pure PPS based DP training
> > sequence.
> >
> > References: https://bugs.freedesktop.org/show_bug.cgi?id=69693
> > Signed-off-by: Jesse Barnes <jbarnes at virtuousgeek.org>
> > ---
> >  drivers/gpu/drm/i915/intel_dp.c | 4 +---
> >  1 file changed, 1 insertion(+), 3 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> > index 1e372d5..cb33b67 100644
> > --- a/drivers/gpu/drm/i915/intel_dp.c
> > +++ b/drivers/gpu/drm/i915/intel_dp.c
> > @@ -1236,9 +1236,7 @@ void ironlake_edp_panel_off(struct intel_dp *intel_dp)
> >         WARN(!intel_dp->want_panel_vdd, "Need VDD to turn off panel\n");
> >
> >         pp = ironlake_get_pp_control(intel_dp);
> > -       /* We need to switch off panel power _and_ force vdd, for otherwise some
> > -        * panels get very unhappy and cease to work. */
> > -       pp &= ~(POWER_TARGET_ON | EDP_FORCE_VDD | PANEL_POWER_RESET | EDP_BLC_ENABLE);
> > +       pp &= ~(POWER_TARGET_ON | PANEL_POWER_RESET | EDP_BLC_ENABLE);
> 
> My understanding is that now you'll keep VDD enabled forever, so the
> panel power is not really being disabled. So the commit message and
> title seem wrong. Is this really what you wanted?
> 
> Please take a look at the last patches of the runtime PM series (I
> made them part of the runtime PM series just for rebasing purposes).

Ah yeah you're right, my earlier patch in a bug was right and here I
did a double negative.

We really want to avoid using VDD force altogether, so if your series
does that I think we're in the clear.

Would be good to get confirmation though on #69693.  If you split out
the series can you post an update to it?

-- 
Jesse Barnes, Intel Open Source Technology Center