Quoting Ville Syrjala (2017-11-08 13:35:55)
> From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
>
> 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@xxxxxxxxxxxxxxx
> Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> Cc: Mark Janes <mark.a.janes@xxxxxxxxx>
> Cc: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
> Cc: Daniel Vetter <daniel.vetter@xxxxxxxx>
> Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
> Cc: Oscar Mateo <oscar.mateo@xxxxxxxxx>
> Cc: Mika Kuoppala <mika.kuoppala@xxxxxxxxxxxxxxx>
> Reported-by: Mark Janes <mark.a.janes@xxxxxxxxx>
> 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@xxxxxxxxxxxxxxx>
CTS remains fixed,
Tested-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
I know of no reason why this should work in this order,
Reviewed-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
(but I didn't know about the v2 requirement either!)
-Chris