[Intel-gfx] [PATCH] drm/i915: Reset dpll_hw_state when selecting a new pll on hsw

[Daniel Vetter]

On Tue, Oct 13, 2015 at 04:00:37PM +0200, Maarten Lankhorst wrote:
> Op 13-10-15 om 15:58 schreef Daniel Vetter:
> > On Tue, Oct 13, 2015 at 03:43:28PM +0200, Maarten Lankhorst wrote:
> >> Op 13-10-15 om 15:35 schreef Daniel Vetter:
> >>> On Tue, Oct 13, 2015 at 03:18:16PM +0200, Maarten Lankhorst wrote:
> >>>> Op 23-09-15 om 17:34 schreef Gabriel Feceoru:
> >>>>> Using 2 connectors (DVI and VGA) will cause wrpll to be set for
> >>>>> INTEL_OUTPUT_HDMI but never reset if switching to INTEL_OUTPUT_VGA
> >>>>>
> >>>>> Supresses errors like these:
> >>>>> [drm:intel_pipe_config_compare [i915]] *ERROR* mismatch in dpll_hw_state.wrpll
> >>>>>
> >>>> Looks like a good idea to always zero it.
> >>> Except that we still have a bunch of cases where we recompute clock state
> >>> but only partially. Can we just move them all up into a common place
> >>> please? That would also catch cases where we simply forget to fill this
> >>> out at all.
> >>>
> >>> One case I noticed is edp in skl_ddi_pll_select, but there's probably
> >>> more.
> >>>
> >> Something like below, with all the memsets for dpll_hw_state removed?
> > I think this will blow up since we recompute clock state only when
> > needs_modeset is true. So needs a bit more intelligence in deciding when
> > to clear it I think.
> Oops you're right. Maybe intel_modeset_clear_plls because that's where all the clock state belongs?

Yeah that might be an even better place, in the loop after the continue;
statement.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch