[Intel-gfx] [PATCH v2] drm/i915: Move init_clock_gating() back to where it was

[Chris Wilson]

Quoting Chris Wilson (2017-11-08 16:18:27)
> Quoting Ville Syrjala (2017-11-08 13:35:55)
> > From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > 
> > Apparently setting up a bunch of GT registers before we've properly
> > initialized the rest of the GT hardware leads to these setting being
> > lost. So looks like I broke HSW with commit b7048ea12fbb ("drm/i915:
> > Do .init_clock_gating() earlier to avoid it clobbering watermarks")
> > by doing init_clock_gating() too early. This should actually affect
> > other platforms as well, but apparently not to such a great degree.
> > 
> > What I was ultimately after in that commit was to move the
> > ilk_init_lp_watermarks() call earlier. So let's undo the damage and
> > move init_clock_gating() back to where it was, and call
> > ilk_init_lp_watermarks() just before the watermark state readout.
> > 
> > This highlights how fragile and messed up our init order really is.
> > I wonder why we even initialize the display before gem. The opposite
> > order would make much more sense to me...
> > 
> > v2: Keep WaRsPkgCStateDisplayPMReq:hsw early as it really must
> >     be done before all planes might get disabled.
> > 
> > Cc: stable at vger.kernel.org
> > Cc: Chris Wilson <chris at chris-wilson.co.uk>
> > Cc: Mark Janes <mark.a.janes at intel.com>
> > Cc: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
> > Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
> > Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
> > Cc: Oscar Mateo <oscar.mateo at intel.com>
> > Cc: Mika Kuoppala <mika.kuoppala at linux.intel.com>
> > Reported-by: Mark Janes <mark.a.janes at intel.com>
> > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=103549
> > Fixes: b7048ea12fbb ("drm/i915: Do .init_clock_gating() earlier to avoid it clobbering watermarks")
> > References: https://lists.freedesktop.org/archives/intel-gfx/2017-November/145432.html
> > Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> 
> CTS remains fixed,
> Tested-by: Chris Wilson <chris at chris-wilson.co.uk>
> 
> I know of no reason why this should work in this order,
s/should work/should not/work ;)

> Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>
> (but I didn't know about the v2 requirement either!)
> -Chris