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, 27 insertions, 1 deletions

diff --git a/include/drm/drm_writeback.h b/include/drm/drm_writeback.h
index 47662c362743..777c14c847f0 100644
--- a/include/drm/drm_writeback.h
+++ b/include/drm/drm_writeback.h
@@ -80,6 +80,20 @@ struct drm_writeback_connector {
 
 struct drm_writeback_job {
 	/**
+	 * @connector:
+	 *
+	 * Back-pointer to the writeback connector associated with the job
+	 */
+	struct drm_writeback_connector *connector;
+
+	/**
+	 * @prepared:
+	 *
+	 * Set when the job has been prepared with drm_writeback_prepare_job()
+	 */
+	bool prepared;
+
+	/**
 	 * @cleanup_work:
 	 *
 	 * Used to allow drm_writeback_signal_completion to defer dropping the
@@ -98,7 +112,7 @@ struct drm_writeback_job {
 	 * @fb:
 	 *
 	 * Framebuffer to be written to by the writeback connector. Do not set
-	 * directly, use drm_atomic_set_writeback_fb_for_connector()
+	 * directly, use drm_writeback_set_fb()
 	 */
 	struct drm_framebuffer *fb;
 
@@ -108,6 +122,13 @@ struct drm_writeback_job {
 	 * Fence which will signal once the writeback has completed
 	 */
 	struct dma_fence *out_fence;
+
+	/**
+	 * @priv:
+	 *
+	 * Driver-private data
+	 */
+	void *priv;
 };
 
 static inline struct drm_writeback_connector *
@@ -122,6 +143,11 @@ int drm_writeback_connector_init(struct drm_device *dev,
 				 const struct drm_encoder_helper_funcs *enc_helper_funcs,
 				 const u32 *formats, int n_formats);
 
+int drm_writeback_set_fb(struct drm_connector_state *conn_state,
+			 struct drm_framebuffer *fb);
+
+int drm_writeback_prepare_job(struct drm_writeback_job *job);
+
 void drm_writeback_queue_job(struct drm_writeback_connector *wb_connector,
 			     struct drm_connector_state *conn_state);