drm: add support for private planes

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@ti.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

3 files changed, 19 insertions, 7 deletions

diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
index 7710bcb..5e818a8 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,
-		   const uint32_t *formats, uint32_t format_count)
+		   const uint32_t *formats, uint32_t format_count,
+		   bool priv)
 {
 	mutex_lock(&dev->mode_config.mutex);
 
@@ -577,8 +578,16 @@ 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);
 
@@ -593,8 +602,11 @@ 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/drivers/gpu/drm/exynos/exynos_drm_plane.c b/drivers/gpu/drm/exynos/exynos_drm_plane.c
index c785e34..bdcf770 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_plane.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_plane.c
@@ -117,7 +117,7 @@ int exynos_plane_init(struct drm_device *dev, unsigned int nr)
 
 	/* TODO: format */
 	return drm_plane_init(dev, &exynos_plane->base, possible_crtcs,
-			      &exynos_plane_funcs, NULL, 0);
+			      &exynos_plane_funcs, NULL, 0, false);
 }
 
 int exynos_plane_set_zpos_ioctl(struct drm_device *dev, void *data,
diff --git a/drivers/gpu/drm/i915/intel_sprite.c b/drivers/gpu/drm/i915/intel_sprite.c
index b26e7c4..d13989f 100644
--- a/drivers/gpu/drm/i915/intel_sprite.c
+++ b/drivers/gpu/drm/i915/intel_sprite.c
@@ -659,7 +659,7 @@ intel_plane_init(struct drm_device *dev, enum pipe pipe)
 	possible_crtcs = (1 << pipe);
 	ret = drm_plane_init(dev, &intel_plane->base, possible_crtcs,
 			     &intel_plane_funcs, snb_plane_formats,
-			     ARRAY_SIZE(snb_plane_formats));
+			     ARRAY_SIZE(snb_plane_formats), false);
 	if (ret)
 		kfree(intel_plane);