commit bf6811f304795e7697985449ee870b29a8cbc6c7
author Rob Clark <robdclark@gmail.com> Sun Sep 01 13:25:09 2013 -0400
committer Rob Clark <robdclark@gmail.com> Tue Sep 10 13:56:58 2013 -0400
tree 23e844ef2eb4887d6d8f939fc056ffa54b1cbcd7
parent 86a7e1224a68511d3a1ae0b7e11581b9d37723ae

drm/msm: handle read vs write fences

The userspace API already had everything needed to handle read vs write
synchronization.  This patch actually bothers to hook it up properly, so
that we don't need to (for example) stall on userspace read access to a
buffer that gpu is also still reading.

Signed-off-by: Rob Clark <robdclark@gmail.com>

drivers/gpu/drm/msm/msm_gem.c

diff --git a/drivers/gpu/drm/msm/msm_gem.c b/drivers/gpu/drm/msm/msm_gem.c
index 6b5a6c8..df0390f 100644
--- a/drivers/gpu/drm/msm/msm_gem.c
+++ b/drivers/gpu/drm/msm/msm_gem.c
@@ -393,11 +393,14 @@
 }
 
 void msm_gem_move_to_active(struct drm_gem_object *obj,
-		struct msm_gpu *gpu, uint32_t fence)
+		struct msm_gpu *gpu, bool write, uint32_t fence)
 {
 	struct msm_gem_object *msm_obj = to_msm_bo(obj);
 	msm_obj->gpu = gpu;
-	msm_obj->fence = fence;
+	if (write)
+		msm_obj->write_fence = fence;
+	else
+		msm_obj->read_fence = fence;
 	list_del_init(&msm_obj->mm_list);
 	list_add_tail(&msm_obj->mm_list, &gpu->active_list);
 }
@@ -411,7 +414,8 @@
 	WARN_ON(!mutex_is_locked(&dev->struct_mutex));
 
 	msm_obj->gpu = NULL;
-	msm_obj->fence = 0;
+	msm_obj->read_fence = 0;
+	msm_obj->write_fence = 0;
 	list_del_init(&msm_obj->mm_list);
 	list_add_tail(&msm_obj->mm_list, &priv->inactive_list);
 
@@ -433,8 +437,14 @@
 	struct msm_gem_object *msm_obj = to_msm_bo(obj);
 	int ret = 0;
 
-	if (is_active(msm_obj) && !(op & MSM_PREP_NOSYNC))
-		ret = msm_wait_fence_interruptable(dev, msm_obj->fence, timeout);
+	if (is_active(msm_obj) && !(op & MSM_PREP_NOSYNC)) {
+		uint32_t fence = 0;
+		if (op & MSM_PREP_READ)
+			fence = msm_obj->write_fence;
+		if (op & MSM_PREP_WRITE)
+			fence = max(fence, msm_obj->read_fence);
+		ret = msm_wait_fence_interruptable(dev, fence, timeout);
+	}
 
 	/* TODO cache maintenance */
 
@@ -455,9 +465,10 @@
 	uint64_t off = drm_vma_node_start(&obj->vma_node);
 
 	WARN_ON(!mutex_is_locked(&dev->struct_mutex));
-	seq_printf(m, "%08x: %c(%d) %2d (%2d) %08llx %p %d\n",
+	seq_printf(m, "%08x: %c(r=%u,w=%u) %2d (%2d) %08llx %p %d\n",
 			msm_obj->flags, is_active(msm_obj) ? 'A' : 'I',
-			msm_obj->fence, obj->name, obj->refcount.refcount.counter,
+			msm_obj->read_fence, msm_obj->write_fence,
+			obj->name, obj->refcount.refcount.counter,
 			off, msm_obj->vaddr, obj->size);
 }