isl: Set MOCS to uncached for Gfx12.0 blitter sources/destinations

We were accidentally leaving XY_BLOCK_COPY_BLT's Source and Destination
MOCS fields set to 0 (Error: Reserved for Non-Use) on Gfx12.0 systems.
This was causing assert fails in debug builds, since we try to ensure
that we don't do that.  In theory, MOCS 0 is supposed to be equivalent
to MOCS 2 (all the caching), but...we probably ought to use MOCS 3
(uncached).  Every Gfx12.5+ platform requires it, so although there
isn't a note about Gfx12.0 needing that, it's possible that it does.
We're currently only using the blitter for DRI PRIME blits on Gfx12.0,
anyway, and I think we're flushing all the caches regardless.

This bug was somewhat obscure to hit:
- You need a hybrid graphics system with Gfx12.0 and some other GPU
- You have to be using "reverse PRIME", i.e. rendering on the integrated
  GPU and displaying on the discrete one.  This is not the common case.
- You have to be using a debug build.

No observable performance delta in GfxBench5 Car Chase (an arbitrary
program) when rendering on Alderlake GT1 and displaying on an Arc A770.

Fixes: 194afe84163 ("anv/iris/blorp: use the right MOCS values for each engine")
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Reviewed-by: Rohan Garg <rohan.garg@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/28894>
(cherry picked from commit e6fb3ba03798fc2550bdb5ec6651690a34ac3509)

2 files changed, 7 insertions, 1 deletions

diff --git a/.pick_status.json b/.pick_status.json
index 8bc94ebed8f..df4dfd56538 100644
--- a/.pick_status.json
+++ b/.pick_status.json
@@ -2514,7 +2514,7 @@
         "description": "isl: Set MOCS to uncached for Gfx12.0 blitter sources/destinations",
         "nominated": true,
         "nomination_type": 1,
-        "resolution": 0,
+        "resolution": 1,
         "main_sha": null,
         "because_sha": "194afe841635e43d55c4f71f4122c6048f585450",
         "notes": null
diff --git a/src/intel/isl/isl.c b/src/intel/isl/isl.c
index 1e19db1c903..3793ea5d929 100644
--- a/src/intel/isl/isl.c
+++ b/src/intel/isl/isl.c
@@ -175,6 +175,8 @@ isl_device_setup_mocs(struct isl_device *dev)
          dev->mocs.external = 5 << 1;
          /* UC */
          dev->mocs.uncached = 1 << 1;
+         dev->mocs.blitter_dst = 1 << 1;
+         dev->mocs.blitter_src = 1 << 1;
       } else {
          /* TC=1/LLC Only, LeCC=1/UC, LRUM=0, L3CC=3/WB */
          dev->mocs.external = 61 << 1;
@@ -185,6 +187,10 @@ isl_device_setup_mocs(struct isl_device *dev)
 
          /* L1 - HDC:L1 + L3 + LLC */
          dev->mocs.l1_hdc_l3_llc = 48 << 1;
+
+         /* Uncached */
+         dev->mocs.blitter_dst = 3 << 1;
+         dev->mocs.blitter_src = 3 << 1;
       }
       /* Protected is just an additional flag. */
       dev->mocs.protected_mask = 1 << 0;