On 04/05/2022 17:48, Matt Roper wrote:
On Wed, May 04, 2022 at 01:07:14PM +0100, Tvrtko Ursulin wrote:
From: Tvrtko Ursulin <[email protected]>

DRM_DEBUG_WARN_ON should only be used when we are certain CI is guaranteed
to exercise a certain code path, so in case of values coming from MMIO
reads we cannot be sure CI will have all the possible SKUs and parts.

Use drm_warn instead and move logging to init phase while at it.

Changing to drm_warn looks good, although moving the location changes
the intent a bit; I think originally the idea was to warn if we were
trying to do a steering lookup for a type that we never initialized
(e.g., an LNCF lookup for a !HAS_MSLICES platform where we never even
read the register in the first place).  But I don't think we've ever
made a mistake that would cause us to trip the warning, so it probably
isn't terribly important to keep it there.

Ah I see.. there we could put something like:

        case MSLICE:
                GEM_WARN_ON(!HAS_MSLICES(...));

?

Regards,

Tvrtko


Reviewed-by: Matt Roper <[email protected]>


Signed-off-by: Tvrtko Ursulin <[email protected]>
Cc: Matt Roper <[email protected]>
Cc: Jani Nikula <[email protected]>
---
  drivers/gpu/drm/i915/gt/intel_gt.c | 13 ++++++-------
  1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/intel_gt.c 
b/drivers/gpu/drm/i915/gt/intel_gt.c
index 53307ca0eed0..c474e5c3ea5e 100644
--- a/drivers/gpu/drm/i915/gt/intel_gt.c
+++ b/drivers/gpu/drm/i915/gt/intel_gt.c
@@ -153,11 +153,14 @@ int intel_gt_init_mmio(struct intel_gt *gt)
         * An mslice is unavailable only if both the meml3 for the slice is
         * disabled *and* all of the DSS in the slice (quadrant) are disabled.
         */
-       if (HAS_MSLICES(i915))
+       if (HAS_MSLICES(i915)) {
                gt->info.mslice_mask =
                        slicemask(gt, GEN_DSS_PER_MSLICE) |
                        (intel_uncore_read(gt->uncore, GEN10_MIRROR_FUSE3) &
                         GEN12_MEML3_EN_MASK);
+               if (!gt->info.mslice_mask) /* should be impossible! */
+                       drm_warn(&i915->drm, "mslice mask all zero!\n");
+       }
if (IS_DG2(i915)) {
                gt->steering_table[MSLICE] = xehpsdv_mslice_steering_table;
@@ -171,6 +174,8 @@ int intel_gt_init_mmio(struct intel_gt *gt)
                gt->info.l3bank_mask =
                        ~intel_uncore_read(gt->uncore, GEN10_MIRROR_FUSE3) &
                        GEN10_L3BANK_MASK;
+               if (!gt->info.l3bank_mask) /* should be impossible! */
+                       drm_warn(&i915->drm, "L3 bank mask is all zero!\n");
        } else if (HAS_MSLICES(i915)) {
                MISSING_CASE(INTEL_INFO(i915)->platform);
        }
@@ -882,20 +887,14 @@ static void intel_gt_get_valid_steering(struct intel_gt 
*gt,
  {
        switch (type) {
        case L3BANK:
-               GEM_DEBUG_WARN_ON(!gt->info.l3bank_mask); /* should be 
impossible! */
-
                *sliceid = 0;           /* unused */
                *subsliceid = __ffs(gt->info.l3bank_mask);
                break;
        case MSLICE:
-               GEM_DEBUG_WARN_ON(!gt->info.mslice_mask); /* should be 
impossible! */
-
                *sliceid = __ffs(gt->info.mslice_mask);
                *subsliceid = 0;        /* unused */
                break;
        case LNCF:
-               GEM_DEBUG_WARN_ON(!gt->info.mslice_mask); /* should be 
impossible! */
-
                /*
                 * An LNCF is always present if its mslice is present, so we
                 * can safely just steer to LNCF 0 in all cases.
--
2.32.0


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