[PATCH 02/35] drm/i915: Stop storing the ring size in the ring pointer (v2)

Jason Ekstrand jason at jlekstrand.net
Fri Jun 4 22:10:42 UTC 2021


Previously, we were storing the ring size in the ring pointer before it
was actually allocated.  We would then guard setting the ring size on
checking for CONTEXT_ALLOC_BIT.  This is error-prone at best and really
only saves us a few bytes on something that already burns at least 4K.
Instead, this patch adds a new ring_size field and makes everything use
that.

v2 (Daniel Vetter):
 - Replace 512 * SZ_4K with SZ_2M

Signed-off-by: Jason Ekstrand <jason at jlekstrand.net>
Reviewed-by: Daniel Vetter <daniel.vetter at ffwll.ch>
---
 drivers/gpu/drm/i915/gem/i915_gem_context.c   | 3 +--
 drivers/gpu/drm/i915/gt/intel_context.c       | 3 ++-
 drivers/gpu/drm/i915/gt/intel_context.h       | 5 -----
 drivers/gpu/drm/i915/gt/intel_context_types.h | 1 +
 drivers/gpu/drm/i915/gt/intel_lrc.c           | 2 +-
 drivers/gpu/drm/i915/gt/selftest_execlists.c  | 2 +-
 drivers/gpu/drm/i915/gt/selftest_mocs.c       | 2 +-
 drivers/gpu/drm/i915/gt/selftest_timeline.c   | 2 +-
 drivers/gpu/drm/i915/gvt/scheduler.c          | 7 ++-----
 9 files changed, 10 insertions(+), 17 deletions(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context.c b/drivers/gpu/drm/i915/gem/i915_gem_context.c
index 650364a0dae28..ec999b7ca50f4 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_context.c
@@ -211,8 +211,7 @@ static void intel_context_set_gem(struct intel_context *ce,
 	GEM_BUG_ON(rcu_access_pointer(ce->gem_context));
 	RCU_INIT_POINTER(ce->gem_context, ctx);
 
-	if (!test_bit(CONTEXT_ALLOC_BIT, &ce->flags))
-		ce->ring = __intel_context_ring_size(SZ_16K);
+	ce->ring_size = SZ_16K;
 
 	if (rcu_access_pointer(ctx->vm)) {
 		struct i915_address_space *vm;
diff --git a/drivers/gpu/drm/i915/gt/intel_context.c b/drivers/gpu/drm/i915/gt/intel_context.c
index 4033184f13b9f..bd63813c8a802 100644
--- a/drivers/gpu/drm/i915/gt/intel_context.c
+++ b/drivers/gpu/drm/i915/gt/intel_context.c
@@ -371,7 +371,8 @@ intel_context_init(struct intel_context *ce, struct intel_engine_cs *engine)
 	ce->engine = engine;
 	ce->ops = engine->cops;
 	ce->sseu = engine->sseu;
-	ce->ring = __intel_context_ring_size(SZ_4K);
+	ce->ring = NULL;
+	ce->ring_size = SZ_4K;
 
 	ewma_runtime_init(&ce->runtime.avg);
 
diff --git a/drivers/gpu/drm/i915/gt/intel_context.h b/drivers/gpu/drm/i915/gt/intel_context.h
index f83a73a2b39fc..b10cbe8fee992 100644
--- a/drivers/gpu/drm/i915/gt/intel_context.h
+++ b/drivers/gpu/drm/i915/gt/intel_context.h
@@ -175,11 +175,6 @@ int intel_context_prepare_remote_request(struct intel_context *ce,
 
 struct i915_request *intel_context_create_request(struct intel_context *ce);
 
-static inline struct intel_ring *__intel_context_ring_size(u64 sz)
-{
-	return u64_to_ptr(struct intel_ring, sz);
-}
-
 static inline bool intel_context_is_barrier(const struct intel_context *ce)
 {
 	return test_bit(CONTEXT_BARRIER_BIT, &ce->flags);
diff --git a/drivers/gpu/drm/i915/gt/intel_context_types.h b/drivers/gpu/drm/i915/gt/intel_context_types.h
index ed8c447a7346b..90026c1771055 100644
--- a/drivers/gpu/drm/i915/gt/intel_context_types.h
+++ b/drivers/gpu/drm/i915/gt/intel_context_types.h
@@ -82,6 +82,7 @@ struct intel_context {
 	spinlock_t signal_lock; /* protects signals, the list of requests */
 
 	struct i915_vma *state;
+	u32 ring_size;
 	struct intel_ring *ring;
 	struct intel_timeline *timeline;
 
diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c b/drivers/gpu/drm/i915/gt/intel_lrc.c
index aafe2a4df4960..890b43b296a90 100644
--- a/drivers/gpu/drm/i915/gt/intel_lrc.c
+++ b/drivers/gpu/drm/i915/gt/intel_lrc.c
@@ -845,7 +845,7 @@ int lrc_alloc(struct intel_context *ce, struct intel_engine_cs *engine)
 	if (IS_ERR(vma))
 		return PTR_ERR(vma);
 
-	ring = intel_engine_create_ring(engine, (unsigned long)ce->ring);
+	ring = intel_engine_create_ring(engine, ce->ring_size);
 	if (IS_ERR(ring)) {
 		err = PTR_ERR(ring);
 		goto err_vma;
diff --git a/drivers/gpu/drm/i915/gt/selftest_execlists.c b/drivers/gpu/drm/i915/gt/selftest_execlists.c
index 1f93591a8c69e..e78f2bd48bac8 100644
--- a/drivers/gpu/drm/i915/gt/selftest_execlists.c
+++ b/drivers/gpu/drm/i915/gt/selftest_execlists.c
@@ -2793,7 +2793,7 @@ static int __live_preempt_ring(struct intel_engine_cs *engine,
 			goto err_ce;
 		}
 
-		tmp->ring = __intel_context_ring_size(ring_sz);
+		tmp->ring_size = ring_sz;
 
 		err = intel_context_pin(tmp);
 		if (err) {
diff --git a/drivers/gpu/drm/i915/gt/selftest_mocs.c b/drivers/gpu/drm/i915/gt/selftest_mocs.c
index e55a887d11e2b..f343fa5fd986f 100644
--- a/drivers/gpu/drm/i915/gt/selftest_mocs.c
+++ b/drivers/gpu/drm/i915/gt/selftest_mocs.c
@@ -28,7 +28,7 @@ static struct intel_context *mocs_context_create(struct intel_engine_cs *engine)
 		return ce;
 
 	/* We build large requests to read the registers from the ring */
-	ce->ring = __intel_context_ring_size(SZ_16K);
+	ce->ring_size = SZ_16K;
 
 	return ce;
 }
diff --git a/drivers/gpu/drm/i915/gt/selftest_timeline.c b/drivers/gpu/drm/i915/gt/selftest_timeline.c
index 9adbd9d147bea..7eedecfb86e59 100644
--- a/drivers/gpu/drm/i915/gt/selftest_timeline.c
+++ b/drivers/gpu/drm/i915/gt/selftest_timeline.c
@@ -874,7 +874,7 @@ static int create_watcher(struct hwsp_watcher *w,
 	if (IS_ERR(ce))
 		return PTR_ERR(ce);
 
-	ce->ring = __intel_context_ring_size(ringsz);
+	ce->ring_size = ringsz;
 	w->rq = intel_context_create_request(ce);
 	intel_context_put(ce);
 	if (IS_ERR(w->rq))
diff --git a/drivers/gpu/drm/i915/gvt/scheduler.c b/drivers/gpu/drm/i915/gvt/scheduler.c
index fc735692f21fb..422cbe0d579d2 100644
--- a/drivers/gpu/drm/i915/gvt/scheduler.c
+++ b/drivers/gpu/drm/i915/gvt/scheduler.c
@@ -1409,11 +1409,8 @@ int intel_vgpu_setup_submission(struct intel_vgpu *vgpu)
 		intel_context_set_single_submission(ce);
 
 		/* Max ring buffer size */
-		if (!intel_uc_wants_guc_submission(&engine->gt->uc)) {
-			const unsigned int ring_size = 512 * SZ_4K;
-
-			ce->ring = __intel_context_ring_size(ring_size);
-		}
+		if (!intel_uc_wants_guc_submission(&engine->gt->uc))
+			ce->ring_size = SZ_2M;
 
 		s->shadow[i] = ce;
 	}
-- 
2.31.1



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