[Intel-gfx] [PATCH] i915_drm: add exec flag to warn kernel that userspace is using predication

[Rodrigo Vivi]

If Userspace isn't using MI_PREDICATE all slices must be enabled for
backward compatibility.

If I915_EXEC_USE_PREDICATE isn't set and defaul is set to half, kernel will force
all slices on.

v2: include more tests and s/GT_FULL/USE_PREDICATE
    on code and on commit message.

Signed-off-by: Rodrigo Vivi <rodrigo.vivi at gmail.com>
---
 include/drm/i915_drm.h | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/include/drm/i915_drm.h b/include/drm/i915_drm.h
index aa983f3..933656c 100644
--- a/include/drm/i915_drm.h
+++ b/include/drm/i915_drm.h
@@ -670,6 +670,12 @@ struct drm_i915_gem_execbuffer2 {
 /** Resets the SO write offset registers for transform feedback on gen7. */
 #define I915_EXEC_GEN7_SOL_RESET	(1<<8)
 
+/* If this flag is set userspace is using predicate and half slices can be
+ * let disabled for power saving. Otherwise use all slices even when disabled
+ * by boot parameter or via sysfs interface
+ */
+#define I915_EXEC_USE_PREDICATE		(1<<13)
+
 #define I915_EXEC_CONTEXT_ID_MASK	(0xffffffff)
 #define i915_execbuffer2_set_context_id(eb2, context) \
 	(eb2).rsvd1 = context & I915_EXEC_CONTEXT_ID_MASK
-- 
1.7.11.7