drm/i915/gt: Program mocs:63 for cache eviction on gen9
Ville noticed that the last mocs entry is used unconditionally by the HW when it performs cache evictions, and noted that while the value is not meant to be writable by the driver, we should program it to a reasonable value nevertheless. As it turns out, we can change the value of mocs:63 and the value we were programming into it would cause hard hangs in conjunction with atomic operations. v2: Add details from bspec about how it is used by HW Suggested-by: Ville Syrjälä <ville.syrjala@linux.intel.com> Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/2707 Fixes: 3bbaba0c ("drm/i915: Added Programming of the MOCS") Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> Cc: Jason Ekstrand <jason@jlekstrand.net> Cc: <stable@vger.kernel.org> # v4.3+ Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20201126140841.1982-1-chris@chris-wilson.co.uk
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