On 4/4/2023 8:27 PM, Ville Syrjälä wrote:
On Tue, Apr 04, 2023 at 08:13:42PM +0200, Nirmoy Das wrote:
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)
v3: use revid as we want to target SOC stepping(Radhakrishna)
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>
Cc: Radhakrishna Sripada <radhakrishna.sripada@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 | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_stolen.c b/drivers/gpu/drm/i915/gem/i915_gem_stolen.c
index 8ac376c24aa2..ee492d823f1b 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_stolen.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_stolen.c
@@ -535,6 +535,14 @@ 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_METEORLAKE(i915) && INTEL_REVID(i915) == 0x0)
+ i915->dsm.usable_size = 0;
That certainly won't prevent FBC from using stolen.
Are we sure that FBC accesses are fine?
I think so. I remember Jouni tested this patch internally to unblock a
FBC test.
Jouni, could you please share your thoughts. I can't seem to find the
internal JIRA reference right now.
Regards,
Nirmoy
+
return 0;
}
--
2.39.0
