i965/gen9: Use custom MOCS entries set up by the kernel.

Instead of relying on hardware defaults the i915 kernel driver is
going program custom MOCS tables system-wide on Gen9 hardware.  The
"WT" entry previously used for renderbuffers had a number of problems:
It disabled caching on eLLC, it used a reserved L3 cacheability
setting, and it used to override the PTE controls making renderbuffers
always WT on LLC regardless of the kernel's setting.  Instead use an
entry from the new MOCS tables with parameters: TC=LLC/eLLC, LeCC=PTE,
L3CC=WB.

The "WB" entry previously used for anything other than renderbuffers
has moved to a different index in the new MOCS tables but it should
have the same caching semantics as the old entry.

Even though the corresponding kernel change ("drm/i915: Added
Programming of the MOCS") is in a way an ABI break it doesn't seem
necessary to check that the kernel is recent enough because the change
should only affect Gen9 which is still unreleased hardware.

v2: Update MOCS values for the new Android-incompatible tables
    introduced in v7 of the kernel patch.

Cc: 10.6 <mesa-stable@lists.freedesktop.org>
Reference: http://lists.freedesktop.org/archives/intel-gfx/2015-July/071080.html
Reviewed-by: Ben Widawsky <ben@bwidawsk.net>

diff --git a/src/mesa/drivers/dri/i965/brw_defines.h b/src/mesa/drivers/dri/i965/brw_defines.h
index b1a1c11b3ae481d127ec00365b452f8ce28cf729..5bf53e375e8e90123a9d8490706b8e3f30a5b9f3 100644 (file)
--- a/src/mesa/drivers/dri/i965/brw_defines.h
+++ b/src/mesa/drivers/dri/i965/brw_defines.h
@@ -2492,12 +2492,13 @@ enum brw_wm_barycentric_interp_mode {
 #define BDW_MOCS_WT  0x58
 #define BDW_MOCS_PTE 0x18
 
-/* Skylake: MOCS is now an index into an array of 64 different configurable
- * cache settings.  We still use only either write-back or write-through; and
- * rely on the documented default values.
+/* Skylake: MOCS is now an index into an array of 62 different caching
+ * configurations programmed by the kernel.
  */
-#define SKL_MOCS_WB (0b001001 << 1)
-#define SKL_MOCS_WT (0b000101 << 1)
+/* TC=LLC/eLLC, LeCC=WB, LRUM=3, L3CC=WB */
+#define SKL_MOCS_WB  (2 << 1)
+/* TC=LLC/eLLC, LeCC=PTE, LRUM=3, L3CC=WB */
+#define SKL_MOCS_PTE (1 << 1)
 
 #define MEDIA_VFE_STATE                         0x7000
 /* GEN7 DW2, GEN8+ DW3 */

diff --git a/src/mesa/drivers/dri/i965/gen8_surface_state.c b/src/mesa/drivers/dri/i965/gen8_surface_state.c
index bd3eb00a4394977c94da93950f261ed040326c54..6c4d3e197a51e4025515fc7544f1c2b26b558887 100644 (file)
--- a/src/mesa/drivers/dri/i965/gen8_surface_state.c
+++ b/src/mesa/drivers/dri/i965/gen8_surface_state.c
@@ -401,8 +401,7 @@ gen8_update_renderbuffer_surface(struct brw_context *brw,
       irb->mt_layer : (irb->mt_layer / MAX2(mt->num_samples, 1));
    GLenum gl_target =
       rb->TexImage ? rb->TexImage->TexObject->Target : GL_TEXTURE_2D;
-   /* FINISHME: Use PTE MOCS on Skylake. */
-   uint32_t mocs = brw->gen >= 9 ? SKL_MOCS_WT : BDW_MOCS_PTE;
+   const uint32_t mocs = brw->gen >= 9 ? SKL_MOCS_PTE : BDW_MOCS_PTE;
 
    intel_miptree_used_for_rendering(mt);