[Intel-gfx] [PATCH 4/6] drm/i915: Skip CS verification of L3 bank registers

[Tvrtko Ursulin]

From: Tvrtko Ursulin <tvrtko.ursu...@intel.com>

Access to 0xb100 - 0xb3ff mmio range is controlled by the MCR selector
which only affects CPU MMIO. Therefore these registers cannot be realiably
read with MI_SRM from the command streamer so skip their verification.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursu...@intel.com>
---
 drivers/gpu/drm/i915/gt/intel_workarounds.c | 38 ++++++++++++++++++---
 1 file changed, 33 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/intel_workarounds.c 
b/drivers/gpu/drm/i915/gt/intel_workarounds.c
index c2325b7ecf8d..619d42a2b81b 100644
--- a/drivers/gpu/drm/i915/gt/intel_workarounds.c
+++ b/drivers/gpu/drm/i915/gt/intel_workarounds.c
@@ -1436,26 +1436,50 @@ create_scratch(struct i915_address_space *vm, int count)
        return ERR_PTR(err);
 }
 
+static bool mcr_range(struct drm_i915_private *i915, u32 offset)
+{
+       /*
+        * Registers in this range are affected by the MCR selector
+        * which only controls CPU initiated MMIO. Routing does not
+        * work for CS access so we cannot verify them on this path.
+        */
+       if (INTEL_GEN(i915) >= 8 && (offset >= 0xb100 && offset <= 0xb3ff))
+               return true;
+
+       return false;
+}
+
 static int
 wa_list_srm(struct i915_request *rq,
            const struct i915_wa_list *wal,
            struct i915_vma *vma)
 {
+       struct drm_i915_private *i915 = rq->i915;
+       unsigned int i, count = 0;
        const struct i915_wa *wa;
-       unsigned int i;
        u32 srm, *cs;
 
        srm = MI_STORE_REGISTER_MEM | MI_SRM_LRM_GLOBAL_GTT;
-       if (INTEL_GEN(rq->i915) >= 8)
+       if (INTEL_GEN(i915) >= 8)
                srm++;
 
-       cs = intel_ring_begin(rq, 4 * wal->count);
+       for (i = 0, wa = wal->list; i < wal->count; i++, wa++) {
+               if (!mcr_range(i915, i915_mmio_reg_offset(wa->reg)))
+                       count++;
+       }
+
+       cs = intel_ring_begin(rq, 4 * count);
        if (IS_ERR(cs))
                return PTR_ERR(cs);
 
        for (i = 0, wa = wal->list; i < wal->count; i++, wa++) {
+               u32 offset = i915_mmio_reg_offset(wa->reg);
+
+               if (mcr_range(i915, offset))
+                       continue;
+
                *cs++ = srm;
-               *cs++ = i915_mmio_reg_offset(wa->reg);
+               *cs++ = offset;
                *cs++ = i915_ggtt_offset(vma) + sizeof(u32) * i;
                *cs++ = 0;
        }
@@ -1505,9 +1529,13 @@ static int engine_wa_list_verify(struct intel_context 
*ce,
        }
 
        err = 0;
-       for (i = 0, wa = wal->list; i < wal->count; i++, wa++)
+       for (i = 0, wa = wal->list; i < wal->count; i++, wa++) {
+               if (mcr_range(rq->i915, i915_mmio_reg_offset(wa->reg)))
+                       continue;
+
                if (!wa_verify(wa, results[i], wal->name, from))
                        err = -ENXIO;
+       }
 
        i915_gem_object_unpin_map(vma->obj);
 
-- 
2.20.1

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