drm/i915: Simplify calling engine->sync_to

Since requests can no longer be generated as a side-effect of
intel_ring_begin(), we know that the seqno will be unchanged during
ring-emission. This predicatablity then means we do not have to check
for the seqno wrapping around whilst emitting the semaphore for
engine->sync_to().

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1469432687-22756-31-git-send-email-chris@chris-wilson.co.uk
Link: http://patchwork.freedesktop.org/patch/msgid/1470174640-18242-22-git-send-email-chris@chris-wilson.co.uk

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 49ce21a..9b18b9c 100644 (file)
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1757,7 +1757,7 @@ struct drm_i915_private {
        struct i915_gem_context *kernel_context;
        struct intel_engine_cs engine[I915_NUM_ENGINES];
        struct drm_i915_gem_object *semaphore_obj;
-       uint32_t last_seqno, next_seqno;
+       u32 next_seqno;
 
        struct drm_dma_handle *status_page_dmah;
        struct resource mch_res;

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index d79b949..3df6b48 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -2867,22 +2867,15 @@ __i915_gem_object_sync(struct drm_i915_gem_object *obj,
                i915_gem_object_retire_request(obj, from);
        } else {
                int idx = intel_engine_sync_index(from->engine, to->engine);
-               u32 seqno = i915_gem_request_get_seqno(from);
-
-               if (seqno <= from->engine->semaphore.sync_seqno[idx])
+               if (from->fence.seqno <= from->engine->semaphore.sync_seqno[idx])
                        return 0;
 
                trace_i915_gem_ring_sync_to(to, from);
-               ret = to->engine->semaphore.sync_to(to, from->engine, seqno);
+               ret = to->engine->semaphore.sync_to(to, from);
                if (ret)
                        return ret;
 
-               /* We use last_read_req because sync_to()
-                * might have just caused seqno wrap under
-                * the radar.
-                */
-               from->engine->semaphore.sync_seqno[idx] =
-                       i915_gem_request_get_seqno(obj->last_read_req[from->engine->id]);
+               from->engine->semaphore.sync_seqno[idx] = from->fence.seqno;
        }
 
        return 0;

diff --git a/drivers/gpu/drm/i915/i915_gem_request.c b/drivers/gpu/drm/i915/i915_gem_request.c
index e378eb6..11c19e7 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem_request.c
+++ b/drivers/gpu/drm/i915/i915_gem_request.c
@@ -264,14 +264,7 @@ int i915_gem_set_seqno(struct drm_device *dev, u32 seqno)
        if (ret)
                return ret;
 
-       /* Carefully set the last_seqno value so that wrap
-        * detection still works
-        */
        dev_priv->next_seqno = seqno;
-       dev_priv->last_seqno = seqno - 1;
-       if (dev_priv->last_seqno == 0)
-               dev_priv->last_seqno--;
-
        return 0;
 }
 
@@ -288,7 +281,7 @@ static int i915_gem_get_seqno(struct drm_i915_private *dev_priv, u32 *seqno)
                dev_priv->next_seqno = 1;
        }
 
-       *seqno = dev_priv->last_seqno = dev_priv->next_seqno++;
+       *seqno = dev_priv->next_seqno++;
        return 0;
 }
 

diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index 0b6f12c..51f3123 100644 (file)
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -1496,12 +1496,6 @@ static int gen8_render_emit_request(struct drm_i915_gem_request *req)
        return 0;
 }
 
-static inline bool i915_gem_has_seqno_wrapped(struct drm_i915_private *dev_priv,
-                                             u32 seqno)
-{
-       return dev_priv->last_seqno < seqno;
-}
-
 /**
  * intel_ring_sync - sync the waiter to the signaller on seqno
  *
@@ -1511,24 +1505,23 @@ static inline bool i915_gem_has_seqno_wrapped(struct drm_i915_private *dev_priv,
  */
 
 static int
-gen8_ring_sync(struct drm_i915_gem_request *waiter_req,
-              struct intel_engine_cs *signaller,
-              u32 seqno)
+gen8_ring_sync(struct drm_i915_gem_request *wait,
+              struct drm_i915_gem_request *signal)
 {
-       struct intel_ring *waiter = waiter_req->ring;
-       struct drm_i915_private *dev_priv = waiter_req->i915;
-       u64 offset = GEN8_WAIT_OFFSET(waiter_req->engine, signaller->id);
+       struct intel_ring *waiter = wait->ring;
+       struct drm_i915_private *dev_priv = wait->i915;
+       u64 offset = GEN8_WAIT_OFFSET(wait->engine, signal->engine->id);
        struct i915_hw_ppgtt *ppgtt;
        int ret;
 
-       ret = intel_ring_begin(waiter_req, 4);
+       ret = intel_ring_begin(wait, 4);
        if (ret)
                return ret;
 
        intel_ring_emit(waiter, MI_SEMAPHORE_WAIT |
                                MI_SEMAPHORE_GLOBAL_GTT |
                                MI_SEMAPHORE_SAD_GTE_SDD);
-       intel_ring_emit(waiter, seqno);
+       intel_ring_emit(waiter, signal->fence.seqno);
        intel_ring_emit(waiter, lower_32_bits(offset));
        intel_ring_emit(waiter, upper_32_bits(offset));
        intel_ring_advance(waiter);
@@ -1538,48 +1531,37 @@ gen8_ring_sync(struct drm_i915_gem_request *waiter_req,
         * We do this on the i915_switch_context() following the wait and
         * before the dispatch.
         */
-       ppgtt = waiter_req->ctx->ppgtt;
-       if (ppgtt && waiter_req->engine->id != RCS)
-               ppgtt->pd_dirty_rings |= intel_engine_flag(waiter_req->engine);
+       ppgtt = wait->ctx->ppgtt;
+       if (ppgtt && wait->engine->id != RCS)
+               ppgtt->pd_dirty_rings |= intel_engine_flag(wait->engine);
        return 0;
 }
 
 static int
-gen6_ring_sync(struct drm_i915_gem_request *waiter_req,
-              struct intel_engine_cs *signaller,
-              u32 seqno)
+gen6_ring_sync(struct drm_i915_gem_request *wait,
+              struct drm_i915_gem_request *signal)
 {
-       struct intel_ring *waiter = waiter_req->ring;
+       struct intel_ring *waiter = wait->ring;
        u32 dw1 = MI_SEMAPHORE_MBOX |
                  MI_SEMAPHORE_COMPARE |
                  MI_SEMAPHORE_REGISTER;
-       u32 wait_mbox = signaller->semaphore.mbox.wait[waiter_req->engine->id];
+       u32 wait_mbox = signal->engine->semaphore.mbox.wait[wait->engine->id];
        int ret;
 
-       /* Throughout all of the GEM code, seqno passed implies our current
-        * seqno is >= the last seqno executed. However for hardware the
-        * comparison is strictly greater than.
-        */
-       seqno -= 1;
-
        WARN_ON(wait_mbox == MI_SEMAPHORE_SYNC_INVALID);
 
-       ret = intel_ring_begin(waiter_req, 4);
+       ret = intel_ring_begin(wait, 4);
        if (ret)
                return ret;
 
-       /* If seqno wrap happened, omit the wait with no-ops */
-       if (likely(!i915_gem_has_seqno_wrapped(waiter_req->i915, seqno))) {
-               intel_ring_emit(waiter, dw1 | wait_mbox);
-               intel_ring_emit(waiter, seqno);
-               intel_ring_emit(waiter, 0);
-               intel_ring_emit(waiter, MI_NOOP);
-       } else {
-               intel_ring_emit(waiter, MI_NOOP);
-               intel_ring_emit(waiter, MI_NOOP);
-               intel_ring_emit(waiter, MI_NOOP);
-               intel_ring_emit(waiter, MI_NOOP);
-       }
+       intel_ring_emit(waiter, dw1 | wait_mbox);
+       /* Throughout all of the GEM code, seqno passed implies our current
+        * seqno is >= the last seqno executed. However for hardware the
+        * comparison is strictly greater than.
+        */
+       intel_ring_emit(waiter, signal->fence.seqno - 1);
+       intel_ring_emit(waiter, 0);
+       intel_ring_emit(waiter, MI_NOOP);
        intel_ring_advance(waiter);
 
        return 0;

diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h
index c3d4b88..c0b7ce3 100644 (file)
--- a/drivers/gpu/drm/i915/intel_ringbuffer.h
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
@@ -277,9 +277,8 @@ struct intel_engine_cs {
                };
 
                /* AKA wait() */
-               int     (*sync_to)(struct drm_i915_gem_request *to_req,
-                                  struct intel_engine_cs *from,
-                                  u32 seqno);
+               int     (*sync_to)(struct drm_i915_gem_request *to,
+                                  struct drm_i915_gem_request *from);
                int     (*signal)(struct drm_i915_gem_request *signaller_req);
        } semaphore;