drm/nouveau: reduce usage of fence spinlock to when absolutely necessary

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

4 files changed, 8 insertions, 31 deletions

diff --git a/drivers/gpu/drm/nouveau/nouveau_channel.c b/drivers/gpu/drm/nouveau/nouveau_channel.c
index 53daeba4581e..90fdcda332be 100644
--- a/drivers/gpu/drm/nouveau/nouveau_channel.c
+++ b/drivers/gpu/drm/nouveau/nouveau_channel.c
@@ -258,9 +258,7 @@ nouveau_channel_free(struct nouveau_channel *chan)
         nouveau_debugfs_channel_fini(chan);
 
         /* Give outstanding push buffers a chance to complete */
-        spin_lock_irqsave(&chan->fence.lock, flags);
         nouveau_fence_update(chan);
-        spin_unlock_irqrestore(&chan->fence.lock, flags);
         if (chan->fence.sequence != chan->fence.sequence_ack) {
                 struct nouveau_fence *fence = NULL;
 
diff --git a/drivers/gpu/drm/nouveau/nouveau_drv.h b/drivers/gpu/drm/nouveau/nouveau_drv.h
index 47fa28ddec75..587a0ab1fe67 100644
--- a/drivers/gpu/drm/nouveau/nouveau_drv.h
+++ b/drivers/gpu/drm/nouveau/nouveau_drv.h
@@ -188,7 +188,7 @@ struct nouveau_channel {
                 struct list_head pending;
                 uint32_t sequence;
                 uint32_t sequence_ack;
-                uint32_t last_sequence_irq;
+                atomic_t last_sequence_irq;
         } fence;
 
         /* DMA push buffer */
@@ -1111,7 +1111,6 @@ extern int nouveau_fence_wait(void *obj, void *arg, bool lazy, bool intr);
 extern int nouveau_fence_flush(void *obj, void *arg);
 extern void nouveau_fence_unref(void **obj);
 extern void *nouveau_fence_ref(void *obj);
-extern void nouveau_fence_handler(struct drm_device *dev, int channel);
 
 /* nouveau_gem.c */
 extern int nouveau_gem_new(struct drm_device *, struct nouveau_channel *,
diff --git a/drivers/gpu/drm/nouveau/nouveau_fence.c b/drivers/gpu/drm/nouveau/nouveau_fence.c
index faddf53ff9ed..813d853b741b 100644
--- a/drivers/gpu/drm/nouveau/nouveau_fence.c
+++ b/drivers/gpu/drm/nouveau/nouveau_fence.c
@@ -67,12 +67,13 @@ nouveau_fence_update(struct nouveau_channel *chan)
         if (USE_REFCNT)
                 sequence = nvchan_rd32(chan, 0x48);
         else
-                sequence = chan->fence.last_sequence_irq;
+                sequence = atomic_read(&chan->fence.last_sequence_irq);
 
         if (chan->fence.sequence_ack == sequence)
                 return;
         chan->fence.sequence_ack = sequence;
 
+        spin_lock(&chan->fence.lock);
         list_for_each_safe(entry, tmp, &chan->fence.pending) {
                 fence = list_entry(entry, struct nouveau_fence, entry);
 
@@ -84,6 +85,7 @@ nouveau_fence_update(struct nouveau_channel *chan)
                 if (sequence == chan->fence.sequence_ack)
                         break;
         }
+        spin_unlock(&chan->fence.lock);
 }
 
 int
@@ -119,7 +121,6 @@ nouveau_fence_emit(struct nouveau_fence *fence)
 {
         struct drm_nouveau_private *dev_priv = fence->channel->dev->dev_private;
         struct nouveau_channel *chan = fence->channel;
-        unsigned long flags;
         int ret;
 
         ret = RING_SPACE(chan, 2);
@@ -127,9 +128,7 @@ nouveau_fence_emit(struct nouveau_fence *fence)
                 return ret;
 
         if (unlikely(chan->fence.sequence == chan->fence.sequence_ack - 1)) {
-                spin_lock_irqsave(&chan->fence.lock, flags);
                 nouveau_fence_update(chan);
-                spin_unlock_irqrestore(&chan->fence.lock, flags);
 
                 BUG_ON(chan->fence.sequence ==
                        chan->fence.sequence_ack - 1);
@@ -138,9 +137,9 @@ nouveau_fence_emit(struct nouveau_fence *fence)
         fence->sequence = ++chan->fence.sequence;
 
         kref_get(&fence->refcount);
-        spin_lock_irqsave(&chan->fence.lock, flags);
+        spin_lock(&chan->fence.lock);
         list_add_tail(&fence->entry, &chan->fence.pending);
-        spin_unlock_irqrestore(&chan->fence.lock, flags);
+        spin_unlock(&chan->fence.lock);
 
         BEGIN_RING(chan, NvSubSw, USE_REFCNT ? 0x0050 : 0x0150, 1);
         OUT_RING(chan, fence->sequence);
@@ -173,14 +172,11 @@ nouveau_fence_signalled(void *sync_obj, void *sync_arg)
 {
         struct nouveau_fence *fence = nouveau_fence(sync_obj);
         struct nouveau_channel *chan = fence->channel;
-        unsigned long flags;
 
         if (fence->signalled)
                 return true;
 
-        spin_lock_irqsave(&chan->fence.lock, flags);
         nouveau_fence_update(chan);
-        spin_unlock_irqrestore(&chan->fence.lock, flags);
         return fence->signalled;
 }
 
@@ -221,27 +217,12 @@ nouveau_fence_flush(void *sync_obj, void *sync_arg)
         return 0;
 }
 
-void
-nouveau_fence_handler(struct drm_device *dev, int channel)
-{
-        struct drm_nouveau_private *dev_priv = dev->dev_private;
-        struct nouveau_channel *chan = NULL;
-
-        if (channel >= 0 && channel < dev_priv->engine.fifo.channels)
-                chan = dev_priv->fifos[channel];
-
-        if (chan) {
-                spin_lock_irq(&chan->fence.lock);
-                nouveau_fence_update(chan);
-                spin_unlock_irq(&chan->fence.lock);
-        }
-}
-
 int
 nouveau_fence_init(struct nouveau_channel *chan)
 {
         INIT_LIST_HEAD(&chan->fence.pending);
         spin_lock_init(&chan->fence.lock);
+        atomic_set(&chan->fence.last_sequence_irq, 0);
         return 0;
 }
 
diff --git a/drivers/gpu/drm/nouveau/nv04_graph.c b/drivers/gpu/drm/nouveau/nv04_graph.c
index dd09679d31dc..c8973421b635 100644
--- a/drivers/gpu/drm/nouveau/nv04_graph.c
+++ b/drivers/gpu/drm/nouveau/nv04_graph.c
@@ -527,8 +527,7 @@ static int
 nv04_graph_mthd_set_ref(struct nouveau_channel *chan, int grclass,
                         int mthd, uint32_t data)
 {
-        chan->fence.last_sequence_irq = data;
-        nouveau_fence_handler(chan->dev, chan->id);
+        atomic_set(&chan->fence.last_sequence_irq, data);
         return 0;
 }