drm/i915: Disable AsyncFlip performance optimisations

commit 1c8c38c588ea91f8deeae21284840459d1bb58e3 upstream.

This is a required workarounds for all products, especially on gen6+
where it causes the command streamer to fail to parse instructions
following a WAIT_FOR_EVENT. We use WAIT_FOR_EVENT for synchronising
between the GPU and the display engines, and so this bit being unset may
cause hangs.

References: https://bugzilla.kernel.org/show_bug.cgi?id=52311
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
[bwh: Backported to 3.2:
 - Adjust context
 - s/_MASKED_BIT/GFX_MODE/]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 56d931a..a632513 100644 (file)
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -400,6 +400,7 @@
 #define MI_MODE                0x0209c
 # define VS_TIMER_DISPATCH                             (1 << 6)
 # define MI_FLUSH_ENABLE                               (1 << 12)
+# define ASYNC_FLIP_PERF_DISABLE                       (1 << 14)
 
 #define GEN6_GT_MODE   0x20d0
 #define   GEN6_GT_MODE_HI      (1 << 9)

diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index 93819f8..38a7793 100644 (file)
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -399,12 +399,20 @@ static int init_render_ring(struct intel_ring_buffer *ring)
        if (INTEL_INFO(dev)->gen > 3) {
                int mode = VS_TIMER_DISPATCH << 16 | VS_TIMER_DISPATCH;
                I915_WRITE(MI_MODE, mode);
-               if (IS_GEN7(dev))
-                       I915_WRITE(GFX_MODE_GEN7,
-                                  GFX_MODE_DISABLE(GFX_TLB_INVALIDATE_ALWAYS) |
-                                  GFX_MODE_ENABLE(GFX_REPLAY_MODE));
        }
 
+       /* We need to disable the AsyncFlip performance optimisations in order
+        * to use MI_WAIT_FOR_EVENT within the CS. It should already be
+        * programmed to '1' on all products.
+        */
+       if (INTEL_INFO(dev)->gen >= 6)
+               I915_WRITE(MI_MODE, GFX_MODE_ENABLE(ASYNC_FLIP_PERF_DISABLE));
+
+       if (IS_GEN7(dev))
+               I915_WRITE(GFX_MODE_GEN7,
+                          GFX_MODE_DISABLE(GFX_TLB_INVALIDATE_ALWAYS) |
+                          GFX_MODE_ENABLE(GFX_REPLAY_MODE));
+
        if (INTEL_INFO(dev)->gen >= 5) {
                ret = init_pipe_control(ring);
                if (ret)