drm/i915: We implement WaMiSetContext_Hang

WaMiSetContext_Hang tells us that a MI_NOOP must follow MI_SET_CONTEXT.

The other thing WaMiSetContext_Hang seems to say is that URB_FENCE isn't
allowed to straddle two cachelines. But we don't issue those from the
kernel so we don't care.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c
index f37ae10..fb64ab4 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/i915_gem_context.c
@@ -577,7 +577,10 @@ mi_set_context(struct intel_ring_buffer *ring,
                        MI_SAVE_EXT_STATE_EN |
                        MI_RESTORE_EXT_STATE_EN |
                        hw_flags);
-       /* w/a: MI_SET_CONTEXT must always be followed by MI_NOOP */
+       /*
+        * w/a: MI_SET_CONTEXT must always be followed by MI_NOOP
+        * WaMiSetContext_Hang:snb,ivb,vlv
+        */
        intel_ring_emit(ring, MI_NOOP);
 
        if (IS_GEN7(ring->dev))