drm/i915: Simplify cursor register write sequence
It looks like simply writing all the cursor register every single time might be slightly faster than checking to see of each of them need to be written. So if any other register apart from CURPOS needs to be written let's just write all the registers. CURPOS is left as a special case mainly for 845/865 where we have to disable the cursor to change many of the cursor parameters. This introduces a slight chance of the cursor flickering when things get updated (since we're not currently doing the vblank evade for cursor updates). If we write CURPOS alone then that obviously can't happen. And let's follow the same pattern in the i9xx code just for symmetry. I wasn't able to see a singificant performance difference between this and just writing all the registers unconditionally. Signed-off-by:Ville Syrjälä <ville.syrjala@linux.intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/20170327185546.2977-16-ville.syrjala@linux.intel.com Reviewed-by:
Imre Deak <imre.deak@intel.com>
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