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. v2: remove hsdes reference and fix commit message(Andi) Cc: Matthew Auld <matthew.auld@xxxxxxxxx> Cc: Andi Shyti <andi.shyti@xxxxxxxxxxxxxxx> Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@xxxxxxxxx> Cc: Lucas De Marchi <lucas.demarchi@xxxxxxxxx> Signed-off-by: Nirmoy Das <nirmoy.das@xxxxxxxxx> Reviewed-by: Andi Shyti <andi.shyti@xxxxxxxxxxxxxxx> --- drivers/gpu/drm/i915/gem/i915_gem_stolen.c | 9 +++++++++ 1 file changed, 9 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..bf0f0a5f2a5c 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_stolen.c +++ b/drivers/gpu/drm/i915/gem/i915_gem_stolen.c @@ -535,6 +535,15 @@ 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. + */ + 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
