[PATCH 01/29] drm/i915/gt: Only trust sseu subslice fuse if it is set

Chris Wilson chris at chris-wilson.co.uk
Fri Jan 29 14:55:21 UTC 2021


Since userspace cannot run without any subslices, it seems remarkable
that any system would be configured with all fused off. Ignore the fuse
register if it says 0.

References: https://gitlab.freedesktop.org/drm/intel/-/issues/3022
Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/gt/intel_sseu.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/intel_sseu.c b/drivers/gpu/drm/i915/gt/intel_sseu.c
index 0d9f74aec8fe..99c992db2ce7 100644
--- a/drivers/gpu/drm/i915/gt/intel_sseu.c
+++ b/drivers/gpu/drm/i915/gt/intel_sseu.c
@@ -341,9 +341,10 @@ static void gen9_sseu_info_init(struct intel_gt *gt)
 	 * The subslice disable field is global, i.e. it applies
 	 * to each of the enabled slices.
 	 */
-	subslice_mask = (1 << sseu->max_subslices) - 1;
-	subslice_mask &= ~((fuse2 & GEN9_F2_SS_DIS_MASK) >>
-			   GEN9_F2_SS_DIS_SHIFT);
+	subslice_mask = (fuse2 & GEN9_F2_SS_DIS_MASK) >> GEN9_F2_SS_DIS_SHIFT;
+	if (!subslice_mask) /* Ignore the fuse if it says there is no HW */
+		subslice_mask = ~0u;
+	subslice_mask &= GENMASK(sseu->max_subslices - 1, 0);
 
 	/*
 	 * Iterate through enabled slices and subslices to
-- 
2.20.1



More information about the Intel-gfx-trybot mailing list