drm: writeback: Add job prepare and cleanup operations

As writeback jobs contain a framebuffer, drivers may need to prepare and
cleanup them the same way they can prepare and cleanup framebuffers for
planes. Add two new optional connector helper operations,
.prepare_writeback_job() and .cleanup_writeback_job() to support this.

The job prepare operation is called from
drm_atomic_helper_prepare_planes() to avoid a new atomic commit helper
that would need to be called by all drivers not using
drm_atomic_helper_commit(). The job cleanup operation is called from the
existing drm_writeback_cleanup_job() function, invoked both when
destroying the job as part of a aborted commit, or when the job
completes.

The drm_writeback_job structure is extended with a priv field to let
drivers store per-job data, such as mappings related to the writeback
framebuffer.

For internal plumbing reasons the drm_writeback_job structure needs to
store a back-pointer to the drm_writeback_connector. To avoid pushing
too much writeback-specific knowledge to drm_atomic_uapi.c, create a
drm_writeback_set_fb() function, move the writeback job setup code
there, and set the connector backpointer. The prepare_signaling()
function doesn't need to allocate writeback jobs and can ignore
connectors without a job, as it is called after the writeback jobs are
allocated to store framebuffers, and a writeback fence with a
framebuffer is an invalid configuration that gets rejected by the commit
check.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Reviewed-by: Liviu Dudau <liviu.dudau@arm.com>

1 files changed, 8 insertions, 23 deletions

diff --git a/drivers/gpu/drm/drm_atomic_uapi.c b/drivers/gpu/drm/drm_atomic_uapi.c
index 0aabd401d3ca..8fa77def577f 100644
--- a/drivers/gpu/drm/drm_atomic_uapi.c
+++ b/drivers/gpu/drm/drm_atomic_uapi.c
@@ -647,28 +647,15 @@ drm_atomic_plane_get_property(struct drm_plane *plane,
 	return 0;
 }
 
-static struct drm_writeback_job *
-drm_atomic_get_writeback_job(struct drm_connector_state *conn_state)
-{
-	WARN_ON(conn_state->connector->connector_type != DRM_MODE_CONNECTOR_WRITEBACK);
-
-	if (!conn_state->writeback_job)
-		conn_state->writeback_job =
-			kzalloc(sizeof(*conn_state->writeback_job), GFP_KERNEL);
-
-	return conn_state->writeback_job;
-}
-
 static int drm_atomic_set_writeback_fb_for_connector(
 		struct drm_connector_state *conn_state,
 		struct drm_framebuffer *fb)
 {
-	struct drm_writeback_job *job =
-		drm_atomic_get_writeback_job(conn_state);
-	if (!job)
-		return -ENOMEM;
+	int ret;
 
-	drm_framebuffer_assign(&job->fb, fb);
+	ret = drm_writeback_set_fb(conn_state, fb);
+	if (ret < 0)
+		return ret;
 
 	if (fb)
 		DRM_DEBUG_ATOMIC("Set [FB:%d] for connector state %p\n",
@@ -1158,19 +1145,17 @@ static int prepare_signaling(struct drm_device *dev,
 
 	for_each_new_connector_in_state(state, conn, conn_state, i) {
 		struct drm_writeback_connector *wb_conn;
-		struct drm_writeback_job *job;
 		struct drm_out_fence_state *f;
 		struct dma_fence *fence;
 		s32 __user *fence_ptr;
 
+		if (!conn_state->writeback_job)
+			continue;
+
 		fence_ptr = get_out_fence_for_connector(state, conn);
 		if (!fence_ptr)
 			continue;
 
-		job = drm_atomic_get_writeback_job(conn_state);
-		if (!job)
-			return -ENOMEM;
-
 		f = krealloc(*fence_state, sizeof(**fence_state) *
 			     (*num_fences + 1), GFP_KERNEL);
 		if (!f)
@@ -1192,7 +1177,7 @@ static int prepare_signaling(struct drm_device *dev,
 			return ret;
 		}
 
-		job->out_fence = fence;
+		conn_state->writeback_job->out_fence = fence;
 	}
 
 	/*