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>

5 files changed, 97 insertions, 24 deletions

diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
index 40ac19848034..f89641216a44 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -2261,10 +2261,21 @@ EXPORT_SYMBOL(drm_atomic_helper_commit_cleanup_done);
 int drm_atomic_helper_prepare_planes(struct drm_device *dev,
                                      struct drm_atomic_state *state)
 {
+        struct drm_connector *connector;
+        struct drm_connector_state *new_conn_state;
         struct drm_plane *plane;
         struct drm_plane_state *new_plane_state;
         int ret, i, j;
 
+        for_each_new_connector_in_state(state, connector, new_conn_state, i) {
+                if (!new_conn_state->writeback_job)
+                        continue;
+
+                ret = drm_writeback_prepare_job(new_conn_state->writeback_job);
+                if (ret < 0)
+                        return ret;
+        }
+
         for_each_new_plane_in_state(state, plane, new_plane_state, i) {
                 const struct drm_plane_helper_funcs *funcs;
 
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;
         }
 
         /*
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);
 
diff --git a/include/drm/drm_modeset_helper_vtables.h b/include/drm/drm_modeset_helper_vtables.h
index cfb7be40bed7..8f3602811eb5 100644
--- a/include/drm/drm_modeset_helper_vtables.h
+++ b/include/drm/drm_modeset_helper_vtables.h
@@ -49,6 +49,8 @@
  */
 
 enum mode_set_atomic;
+struct drm_writeback_connector;
+struct drm_writeback_job;
 
 /**
  * struct drm_crtc_helper_funcs - helper operations for CRTCs
@@ -989,6 +991,11 @@ struct drm_connector_helper_funcs {
          */
         void (*atomic_commit)(struct drm_connector *connector,
                               struct drm_connector_state *state);
+
+        int (*prepare_writeback_job)(struct drm_writeback_connector *connector,
+                                     struct drm_writeback_job *job);
+        void (*cleanup_writeback_job)(struct drm_writeback_connector *connector,
+                                      struct drm_writeback_job *job);
 };
 
 /**
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);