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, 44 insertions, 0 deletions

diff --git a/drivers/gpu/drm/drm_writeback.c b/drivers/gpu/drm/drm_writeback.c
index 1b497d3530b5..79ac014701c8 100644
--- a/drivers/gpu/drm/drm_writeback.c
+++ b/drivers/gpu/drm/drm_writeback.c
@@ -239,6 +239,43 @@ fail:
 }
 EXPORT_SYMBOL(drm_writeback_connector_init);
 
+int drm_writeback_set_fb(struct drm_connector_state *conn_state,
+			 struct drm_framebuffer *fb)
+{
+	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);
+		if (!conn_state->writeback_job)
+			return -ENOMEM;
+
+		conn_state->writeback_job->connector =
+			drm_connector_to_writeback(conn_state->connector);
+	}
+
+	drm_framebuffer_assign(&conn_state->writeback_job->fb, fb);
+	return 0;
+}
+
+int drm_writeback_prepare_job(struct drm_writeback_job *job)
+{
+	struct drm_writeback_connector *connector = job->connector;
+	const struct drm_connector_helper_funcs *funcs =
+		connector->base.helper_private;
+	int ret;
+
+	if (funcs->prepare_writeback_job) {
+		ret = funcs->prepare_writeback_job(connector, job);
+		if (ret < 0)
+			return ret;
+	}
+
+	job->prepared = true;
+	return 0;
+}
+EXPORT_SYMBOL(drm_writeback_prepare_job);
+
 /**
  * drm_writeback_queue_job - Queue a writeback job for later signalling
  * @wb_connector: The writeback connector to queue a job on
@@ -275,6 +312,13 @@ EXPORT_SYMBOL(drm_writeback_queue_job);
 
 void drm_writeback_cleanup_job(struct drm_writeback_job *job)
 {
+	struct drm_writeback_connector *connector = job->connector;
+	const struct drm_connector_helper_funcs *funcs =
+		connector->base.helper_private;
+
+	if (job->prepared && funcs->cleanup_writeback_job)
+		funcs->cleanup_writeback_job(connector, job);
+
 	if (job->fb)
 		drm_framebuffer_put(job->fb);