drm/i915: add fence register management to execbuf

Adds code to set up fence registers at execbuf time on pre-965 chips as
necessary.  Also fixes up a few bugs in the pre-965 tile register support
(get_order != ffs).  The number of fences available to the kernel defaults
to the hw limit minus 3 (for legacy X front/back/depth), but a new parameter
allows userspace to override that as needed.

Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Dave Airlie <airlied@linux.ie>
diff --git a/include/drm/i915_drm.h b/include/drm/i915_drm.h
index b3bcf72..912cd52 100644
--- a/include/drm/i915_drm.h
+++ b/include/drm/i915_drm.h
@@ -261,6 +261,7 @@
 #define I915_PARAM_LAST_DISPATCH         3
 #define I915_PARAM_CHIPSET_ID            4
 #define I915_PARAM_HAS_GEM               5
+#define I915_PARAM_NUM_FENCES_AVAIL      6
 
 typedef struct drm_i915_getparam {
 	int param;
@@ -272,6 +273,7 @@
 #define I915_SETPARAM_USE_MI_BATCHBUFFER_START            1
 #define I915_SETPARAM_TEX_LRU_LOG_GRANULARITY             2
 #define I915_SETPARAM_ALLOW_BATCHBUFFER                   3
+#define I915_SETPARAM_NUM_USED_FENCES                     4
 
 typedef struct drm_i915_setparam {
 	int param;