Stolen memory is not usable for MTL A0 stepping beyond
certain access size and we have no control over userspace
access size of /dev/fb which can be backed by stolen memory.
So disable stolen memory backed fb by setting i915->dsm.usable_size
to zero.
Cc: Matthew Auld <matthew.a...@intel.com>
Cc: Andi Shyti <andi.sh...@linux.intel.com>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospu...@intel.com>
Cc: Lucas De Marchi <lucas.demar...@intel.com>
Signed-off-by: Nirmoy Das <nirmoy....@intel.com>
---
drivers/gpu/drm/i915/gem/i915_gem_stolen.c | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_stolen.c
b/drivers/gpu/drm/i915/gem/i915_gem_stolen.c
index d8e06e783e30..56ccfcbdbce1 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_stolen.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_stolen.c
@@ -535,6 +535,16 @@ static int i915_gem_init_stolen(struct intel_memory_region
*mem)
/* Basic memrange allocator for stolen space. */
drm_mm_init(&i915->mm.stolen, 0, i915->dsm.usable_size);
+ /*
+ * Access to stolen lmem beyond certain size for MTL A0 stepping
+ * would crash the machine. Disable stolen lmem for userspace access
+ * by setting usable_size to zero.
+ * hsdes: 22016134735
+ */
+ if (IS_MTL_GRAPHICS_STEP(i915, M, STEP_A0, STEP_B0) ||
+ IS_MTL_GRAPHICS_STEP(i915, P, STEP_A0, STEP_B0))
+ i915->dsm.usable_size = 0;
+
return 0;
}
--
2.39.0
