[Intel-gfx] [PATCH 1/2] drm/i915/gt: Set the PP_DIR registers upon enabling ring submission

[Chris Wilson]

Always prime the page table registers before starting the ring. Even
though we will update these to the per-context page tables during
dispatch, it is prudent to ensure that the registers always point to a
valid PD.

Signed-off-by: Chris Wilson <ch...@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuopp...@linux.intel.com>
---
 .../gpu/drm/i915/gt/intel_ring_submission.c   | 40 ++++++++++++-------
 1 file changed, 26 insertions(+), 14 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/intel_ring_submission.c 
b/drivers/gpu/drm/i915/gt/intel_ring_submission.c
index 9537d4912225..f70b903a98bc 100644
--- a/drivers/gpu/drm/i915/gt/intel_ring_submission.c
+++ b/drivers/gpu/drm/i915/gt/intel_ring_submission.c
@@ -627,6 +627,27 @@ static bool stop_ring(struct intel_engine_cs *engine)
        return (ENGINE_READ(engine, RING_HEAD) & HEAD_ADDR) == 0;
 }
 
+static struct i915_address_space *vm_alias(struct i915_address_space *vm)
+{
+       if (i915_is_ggtt(vm))
+               vm = &i915_vm_to_ggtt(vm)->alias->vm;
+
+       return vm;
+}
+
+static void set_pp_dir(struct intel_engine_cs *engine)
+{
+       struct i915_address_space *vm = vm_alias(engine->gt->vm);
+
+       if (vm) {
+               struct i915_ppgtt *ppgtt = i915_vm_to_ppgtt(vm);
+
+               ENGINE_WRITE(engine, RING_PP_DIR_DCLV, PP_DIR_DCLV_2G);
+               ENGINE_WRITE(engine, RING_PP_DIR_BASE,
+                            px_base(ppgtt->pd)->ggtt_offset << 10);
+       }
+}
+
 static int xcs_resume(struct intel_engine_cs *engine)
 {
        struct drm_i915_private *dev_priv = engine->i915;
@@ -685,6 +706,8 @@ static int xcs_resume(struct intel_engine_cs *engine)
        GEM_BUG_ON(!intel_ring_offset_valid(ring, ring->tail));
        intel_ring_update_space(ring);
 
+       set_pp_dir(engine);
+
        /* First wake the ring up to an empty/idle ring */
        ENGINE_WRITE(engine, RING_HEAD, ring->head);
        ENGINE_WRITE(engine, RING_TAIL, ring->head);
@@ -1161,23 +1184,12 @@ static void ring_context_destroy(struct kref *ref)
        intel_context_free(ce);
 }
 
-static struct i915_address_space *vm_alias(struct intel_context *ce)
-{
-       struct i915_address_space *vm;
-
-       vm = ce->vm;
-       if (i915_is_ggtt(vm))
-               vm = &i915_vm_to_ggtt(vm)->alias->vm;
-
-       return vm;
-}
-
 static int __context_pin_ppgtt(struct intel_context *ce)
 {
        struct i915_address_space *vm;
        int err = 0;
 
-       vm = vm_alias(ce);
+       vm = vm_alias(ce->vm);
        if (vm)
                err = gen6_ppgtt_pin(i915_vm_to_ppgtt((vm)));
 
@@ -1188,7 +1200,7 @@ static void __context_unpin_ppgtt(struct intel_context 
*ce)
 {
        struct i915_address_space *vm;
 
-       vm = vm_alias(ce);
+       vm = vm_alias(ce->vm);
        if (vm)
                gen6_ppgtt_unpin(i915_vm_to_ppgtt(vm));
 }
@@ -1545,7 +1557,7 @@ static int switch_context(struct i915_request *rq)
 
        GEM_BUG_ON(HAS_EXECLISTS(rq->i915));
 
-       ret = switch_mm(rq, vm_alias(ce));
+       ret = switch_mm(rq, vm_alias(ce->vm));
        if (ret)
                return ret;
 
-- 
2.25.0

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