drm/vmwgfx: Be more restrictive when dirtying resources

Currently we flag resources as dirty (GPU contents not yet read back to
the backing MOB) whenever they have been part of a command stream.
Obviously many resources can't be dirty and others can only be dirty when
written to by the GPU. That is when they are either bound to the context as
render-targets, depth-stencil, copy / clear destinations and
stream-output targets, or similarly when there are corresponding views into
them.
So mark resources dirty only in these special cases. Context- and cotable
resources are always marked dirty when referenced.
This is important for upcoming emulated coherent memory, since we can avoid
issuing automatic readbacks to non-dirty resources when the CPU tries to
access part of the backing MOB.

Testing: Unigine Heaven with max GPU memory set to 256MB resulting in
heavy resource thrashing.
---
v2: Addressed review comments by Deepak Rawat.
v3: Added some documentation

Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Deepak Rawat <drawat@vmware.com>

1 files changed, 10 insertions, 11 deletions

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c b/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c
index a7c30e567f09..c8feeaa85143 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c
@@ -365,14 +365,6 @@ static int vmw_resource_do_validate(struct vmw_resource *res,
 			list_add_tail(&res->mob_head, &res->backup->res_list);
 	}
 
-	/*
-	 * Only do this on write operations, and move to
-	 * vmw_resource_unreserve if it can be called after
-	 * backup buffers have been unreserved. Otherwise
-	 * sort out locking.
-	 */
-	res->res_dirty = true;
-
 	return 0;
 
 out_bind_failed:
@@ -386,6 +378,8 @@ out_bind_failed:
  * command submission.
  *
  * @res:               Pointer to the struct vmw_resource to unreserve.
+ * @dirty_set:         Change dirty status of the resource.
+ * @dirty:             When changing dirty status indicates the new status.
  * @switch_backup:     Backup buffer has been switched.
  * @new_backup:        Pointer to new backup buffer if command submission
  *                     switched. May be NULL.
@@ -395,6 +389,8 @@ out_bind_failed:
  * resource lru list, so that it can be evicted if necessary.
  */
 void vmw_resource_unreserve(struct vmw_resource *res,
+			    bool dirty_set,
+			    bool dirty,
 			    bool switch_backup,
 			    struct vmw_buffer_object *new_backup,
 			    unsigned long new_backup_offset)
@@ -422,6 +418,9 @@ void vmw_resource_unreserve(struct vmw_resource *res,
 	if (switch_backup)
 		res->backup_offset = new_backup_offset;
 
+	if (dirty_set)
+		res->res_dirty = dirty;
+
 	if (!res->func->may_evict || res->id == -1 || res->pin_count)
 		return;
 
@@ -696,7 +695,7 @@ void vmw_resource_unbind_list(struct vmw_buffer_object *vbo)
 		if (!res->func->unbind)
 			continue;
 
-		(void) res->func->unbind(res, true, &val_buf);
+		(void) res->func->unbind(res, res->res_dirty, &val_buf);
 		res->backup_dirty = true;
 		res->res_dirty = false;
 		list_del_init(&res->mob_head);
@@ -932,7 +931,7 @@ int vmw_resource_pin(struct vmw_resource *res, bool interruptible)
 	res->pin_count++;
 
 out_no_validate:
-	vmw_resource_unreserve(res, false, NULL, 0UL);
+	vmw_resource_unreserve(res, false, false, false, NULL, 0UL);
 out_no_reserve:
 	mutex_unlock(&dev_priv->cmdbuf_mutex);
 	ttm_write_unlock(&dev_priv->reservation_sem);
@@ -968,7 +967,7 @@ void vmw_resource_unpin(struct vmw_resource *res)
 		ttm_bo_unreserve(&vbo->base);
 	}
 
-	vmw_resource_unreserve(res, false, NULL, 0UL);
+	vmw_resource_unreserve(res, false, false, false, NULL, 0UL);
 
 	mutex_unlock(&dev_priv->cmdbuf_mutex);
 	ttm_read_unlock(&dev_priv->reservation_sem);