[PATCH] drm/i915/gt: WaSetVfGuardbandPreemptionVertexCount (bdw/chv)

[Chris Wilson <chris@chris-wilson.co.uk>]

As a w/a for data corruption, we are told to set the preemption vertex
count to 0x20 on boot. As it is a counter, once contexts are active we
do not expect the value to be retained, so hide it from the wa-list
verification.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
---
 drivers/gpu/drm/i915/gt/intel_workarounds.c | 24 +++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/drivers/gpu/drm/i915/gt/intel_workarounds.c b/drivers/gpu/drm/i915/gt/intel_workarounds.c
index 704ace01e7f5..7628f8463317 100644
--- a/drivers/gpu/drm/i915/gt/intel_workarounds.c
+++ b/drivers/gpu/drm/i915/gt/intel_workarounds.c
@@ -647,6 +647,26 @@ int intel_engine_emit_ctx_wa(struct i915_request *rq)
 	return 0;
 }
 
+static void
+gen8_gt_workarounds_init(struct drm_i915_private *i915,
+			 struct i915_wa_list *wal)
+{
+	/* WaSetVfGuardbandPreemptionVertexCount:bdw,chv */
+	wa_write_masked_or(wal, _MMIO(0x83A4), 0, 0xffff0020);
+}
+
+static void
+bdw_gt_workarounds_init(struct drm_i915_private *i915, struct i915_wa_list *wal)
+{
+	gen8_gt_workarounds_init(i915, wal);
+}
+
+static void
+chv_gt_workarounds_init(struct drm_i915_private *i915, struct i915_wa_list *wal)
+{
+	gen8_gt_workarounds_init(i915, wal);
+}
+
 static void
 gen9_gt_workarounds_init(struct drm_i915_private *i915, struct i915_wa_list *wal)
 {
@@ -907,6 +927,10 @@ gt_init_workarounds(struct drm_i915_private *i915, struct i915_wa_list *wal)
 		bxt_gt_workarounds_init(i915, wal);
 	else if (IS_SKYLAKE(i915))
 		skl_gt_workarounds_init(i915, wal);
+	else if (IS_CHERRYVIEW(i915))
+		chv_gt_workarounds_init(i915, wal);
+	else if (IS_BROADWELL(i915))
+		bdw_gt_workarounds_init(i915, wal);
 	else if (INTEL_GEN(i915) <= 8)
 		return;
 	else
-- 
2.22.0

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