On 17/05/2022 04:20, Matt Roper wrote:
Although gen11 and gen12 architectures supported the concept of multiple
slices, in practice all the platforms that were actually designed only
had a single slice (i.e., note the parameters to 'intel_sseu_set_info'
that we pass for each platform).  We can simplify the code slightly by
dropping the multi-slice logic from gen11+ platforms.

Signed-off-by: Matt Roper <matthew.d.ro...@intel.com>
---
  drivers/gpu/drm/i915/gt/intel_sseu.c | 80 ++++++++++++++--------------
  1 file changed, 40 insertions(+), 40 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/intel_sseu.c 
b/drivers/gpu/drm/i915/gt/intel_sseu.c
index b5fd479a7b85..ade3e1805782 100644
--- a/drivers/gpu/drm/i915/gt/intel_sseu.c
+++ b/drivers/gpu/drm/i915/gt/intel_sseu.c
@@ -119,52 +119,37 @@ static u16 compute_eu_total(const struct sseu_dev_info 
*sseu)
        return total;
  }
-static u32 get_ss_stride_mask(struct sseu_dev_info *sseu, u8 s, u32 ss_en)
-{
-       u32 ss_mask;
-
-       ss_mask = ss_en >> (s * sseu->max_subslices);
-       ss_mask &= GENMASK(sseu->max_subslices - 1, 0);
-
-       return ss_mask;
-}
-
-static void gen11_compute_sseu_info(struct sseu_dev_info *sseu, u8 s_en,
+static void gen11_compute_sseu_info(struct sseu_dev_info *sseu,
                                    u32 g_ss_en, u32 c_ss_en, u16 eu_en)
  {
-       int s, ss;
+       u32 valid_ss_mask = GENMASK(sseu->max_subslices - 1, 0);
+       int ss;
/* g_ss_en/c_ss_en represent entire subslice mask across all slices */
        GEM_BUG_ON(sseu->max_slices * sseu->max_subslices >
                   sizeof(g_ss_en) * BITS_PER_BYTE);
- for (s = 0; s < sseu->max_slices; s++) {
-               if ((s_en & BIT(s)) == 0)
-                       continue;
+       sseu->slice_mask |= BIT(0);
- sseu->slice_mask |= BIT(s);
-
-               /*
-                * XeHP introduces the concept of compute vs geometry DSS. To
-                * reduce variation between GENs around subslice usage, store a
-                * mask for both the geometry and compute enabled masks since
-                * userspace will need to be able to query these masks
-                * independently.  Also compute a total enabled subslice count
-                * for the purposes of selecting subslices to use in a
-                * particular GEM context.
-                */
-               intel_sseu_set_subslices(sseu, s, sseu->compute_subslice_mask,
-                                        get_ss_stride_mask(sseu, s, c_ss_en));
-               intel_sseu_set_subslices(sseu, s, sseu->geometry_subslice_mask,
-                                        get_ss_stride_mask(sseu, s, g_ss_en));
-               intel_sseu_set_subslices(sseu, s, sseu->subslice_mask,
-                                        get_ss_stride_mask(sseu, s,
-                                                           g_ss_en | c_ss_en));
+       /*
+        * XeHP introduces the concept of compute vs geometry DSS. To reduce
+        * variation between GENs around subslice usage, store a mask for both
+        * the geometry and compute enabled masks since userspace will need to
+        * be able to query these masks independently.  Also compute a total
+        * enabled subslice count for the purposes of selecting subslices to
+        * use in a particular GEM context.
+        */
+       intel_sseu_set_subslices(sseu, 0, sseu->compute_subslice_mask,
+                                c_ss_en & valid_ss_mask);
+       intel_sseu_set_subslices(sseu, 0, sseu->geometry_subslice_mask,
+                                g_ss_en & valid_ss_mask);
+       intel_sseu_set_subslices(sseu, 0, sseu->subslice_mask,
+                                (g_ss_en | c_ss_en) & valid_ss_mask);
+
+       for (ss = 0; ss < sseu->max_subslices; ss++)
+               if (intel_sseu_has_subslice(sseu, 0, ss))
+                       sseu_set_eus(sseu, 0, ss, eu_en);
- for (ss = 0; ss < sseu->max_subslices; ss++)
-                       if (intel_sseu_has_subslice(sseu, s, ss))
-                               sseu_set_eus(sseu, s, ss, eu_en);
-       }
        sseu->eu_per_subslice = hweight16(eu_en);
        sseu->eu_total = compute_eu_total(sseu);
  }
@@ -196,7 +181,7 @@ static void xehp_sseu_info_init(struct intel_gt *gt)
                if (eu_en_fuse & BIT(eu))
                        eu_en |= BIT(eu * 2) | BIT(eu * 2 + 1);
- gen11_compute_sseu_info(sseu, 0x1, g_dss_en, c_dss_en, eu_en);
+       gen11_compute_sseu_info(sseu, g_dss_en, c_dss_en, eu_en);
  }
static void gen12_sseu_info_init(struct intel_gt *gt)
@@ -216,8 +201,15 @@ static void gen12_sseu_info_init(struct intel_gt *gt)
         */
        intel_sseu_set_info(sseu, 1, 6, 16);
+ /*
+        * Although gen12 architecture supported multiple slices, TGL, RKL,
+        * DG1, and ADL only had a single slice.
+        */
        s_en = intel_uncore_read(uncore, GEN11_GT_SLICE_ENABLE) &
                GEN11_GT_S_ENA_MASK;
+       if (s_en != 0x1)
+               drm_dbg(&gt->i915->drm, "Slice mask %#x is not the expected 
0x1!\n",

I'd make these drm_warn - drm_dbg feels pointless. Possibly even drm_WARN_ON since it is supposed to be an impossible condition which needs to be super loud if it happens.

Regards,

Tvrtko

+                       s_en);
g_dss_en = intel_uncore_read(uncore, GEN12_GT_GEOMETRY_DSS_ENABLE); @@ -229,7 +221,7 @@ static void gen12_sseu_info_init(struct intel_gt *gt)
                if (eu_en_fuse & BIT(eu))
                        eu_en |= BIT(eu * 2) | BIT(eu * 2 + 1);
- gen11_compute_sseu_info(sseu, s_en, g_dss_en, 0, eu_en);
+       gen11_compute_sseu_info(sseu, g_dss_en, 0, eu_en);
/* TGL only supports slice-level power gating */
        sseu->has_slice_pg = 1;
@@ -248,14 +240,22 @@ static void gen11_sseu_info_init(struct intel_gt *gt)
        else
                intel_sseu_set_info(sseu, 1, 8, 8);
+ /*
+        * Although gen11 architecture supported multiple slices, ICL and
+        * EHL/JSL only had a single slice in practice.
+        */
        s_en = intel_uncore_read(uncore, GEN11_GT_SLICE_ENABLE) &
                GEN11_GT_S_ENA_MASK;
+       if (s_en != 0x1)
+               drm_dbg(&gt->i915->drm, "Slice mask %#x is not the expected 
0x1!\n",
+                       s_en);
+
        ss_en = ~intel_uncore_read(uncore, GEN11_GT_SUBSLICE_DISABLE);
eu_en = ~(intel_uncore_read(uncore, GEN11_EU_DISABLE) &
                  GEN11_EU_DIS_MASK);
- gen11_compute_sseu_info(sseu, s_en, ss_en, 0, eu_en);
+       gen11_compute_sseu_info(sseu, ss_en, 0, eu_en);
/* ICL has no power gating restrictions. */
        sseu->has_slice_pg = 1;

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