drm/i915: Clear scanline waits after disabling the pipe.
If we disable the pipe and the GPU is currently waiting on a scanline
WAIT_FOR_EVENT, the GPU will hang. Fortunately, there is a magic bit
which we can write on i915+ to break this wait after disabling the
pipe.
References:
Bug 29252 - [Arrandale] Hung WAIT_FOR_EVENT when running rss-glx-skyrocket
https://bugs.freedesktop.org/show_bug.cgi?id=29252
Bug 28964 - [i965gm] GPU infinite MI_WAIT_FOR_EVENT while watching video in Totem
https://bugs.freedesktop.org/show_bug.cgi?id=28964
and many others.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index e240de9..5ede5a5 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -295,6 +295,8 @@
#define RING_VALID_MASK 0x00000001
#define RING_VALID 0x00000001
#define RING_INVALID 0x00000000
+#define RING_WAIT_I8XX (1<<0) /* gen2, PRBx_HEAD */
+#define RING_WAIT (1<<11) /* gen3+, PRBx_CTL */
#define PRB1_TAIL 0x02040 /* 915+ only */
#define PRB1_HEAD 0x02044 /* 915+ only */
#define PRB1_START 0x02048 /* 915+ only */