drm/i915/dmc: Also disable HRR event on TGL/ADLS main DMC

Unlike later platforms TGL/ADLS has the half refresh rate (HRR) event
on the main DMC (as opposed to the pipe DMC). Since we're disabling
that event on all later platforms already let's do the same on
TGL/ADLS as well.

There is supposedly a bit somewhere (DMC_CHICKEN on TGL) to make
the handler not do anything, but we don't currently have code
to frob it. Though that bit should be off by default, the ADL+
experience has shown us that trusting any of this isn't a good
idea. So seems safer to just disable all event handlers we know
that we don't need.

Also the TGL/ADLS DMC firmware is apparently using the wrong event
(undelayed vblank) here anyway. It should be using the delayed
vblank event instead (like ADL+ firmware does), but they didn't
release a firmware fix for this and instead just hacked around
this in the Windows driver code :/

v2: Also disable the event on ADLS (Imre)

Cc: Imre Deak <imre.deak@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231213150807.21331-1-ville.syrjala@linux.intel.com


Reviewed-by: Imre Deak <imre.deak@intel.com>