[PATCH 2/2] drm: add support for private planes

[Rob Clark]

From: Rob Clark <rob at ti.com>

In cases where the scanout hw is sufficiently similar between "overlay"
and traditional crtc layers, it might be convenient to allow the driver
to create internal drm_plane helper objects used by the drm_crtc
implementation, rather than duplicate code between the plane and crtc.
A private plane is not exposed to userspace.

Signed-off-by: Rob Clark <rob at ti.com>
---
 drivers/gpu/drm/drm_crtc.c |   22 +++++++++++++++++-----
 include/drm/drm_crtc.h     |    3 ++-
 2 files changed, 19 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
index 6dad421..d73746e 100644
--- a/drivers/gpu/drm/drm_crtc.c
+++ b/drivers/gpu/drm/drm_crtc.c
@@ -557,7 +557,8 @@ EXPORT_SYMBOL(drm_encoder_cleanup);
 int drm_plane_init(struct drm_device *dev, struct drm_plane *plane,
 		   unsigned long possible_crtcs,
 		   const struct drm_plane_funcs *funcs,
-		   uint32_t *formats, uint32_t format_count)
+		   const uint32_t *formats, uint32_t format_count,
+		   bool priv)
 {
 	mutex_lock(&dev->mode_config.mutex);
 
@@ -576,8 +577,16 @@ int drm_plane_init(struct drm_device *dev, struct drm_plane *plane,
 	plane->format_count = format_count;
 	plane->possible_crtcs = possible_crtcs;
 
-	list_add_tail(&plane->head, &dev->mode_config.plane_list);
-	dev->mode_config.num_plane++;
+	/* private planes are not exposed to userspace, but depending on
+	 * display hardware, might be convenient to allow sharing programming
+	 * for the scanout engine with the crtc implementation.
+	 */
+	if (!priv) {
+		list_add_tail(&plane->head, &dev->mode_config.plane_list);
+		dev->mode_config.num_plane++;
+	} else {
+		INIT_LIST_HEAD(&plane->head);
+	}
 
 	mutex_unlock(&dev->mode_config.mutex);
 
@@ -592,8 +601,11 @@ void drm_plane_cleanup(struct drm_plane *plane)
 	mutex_lock(&dev->mode_config.mutex);
 	kfree(plane->format_types);
 	drm_mode_object_put(dev, &plane->base);
-	list_del(&plane->head);
-	dev->mode_config.num_plane--;
+	/* if not added to a list, it must be a private plane */
+	if (!list_empty(&plane->head)) {
+		list_del(&plane->head);
+		dev->mode_config.num_plane--;
+	}
 	mutex_unlock(&dev->mode_config.mutex);
 }
 EXPORT_SYMBOL(drm_plane_cleanup);
diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
index dd55727..1354ef5 100644
--- a/include/drm/drm_crtc.h
+++ b/include/drm/drm_crtc.h
@@ -828,7 +828,8 @@ extern int drm_plane_init(struct drm_device *dev,
 			  struct drm_plane *plane,
 			  unsigned long possible_crtcs,
 			  const struct drm_plane_funcs *funcs,
-			  uint32_t *formats, uint32_t format_count);
+			  const uint32_t *formats, uint32_t format_count,
+			  bool private);
 extern void drm_plane_cleanup(struct drm_plane *plane);
 
 extern void drm_encoder_cleanup(struct drm_encoder *encoder);
-- 
1.7.5.4