[PATCH v5] drm/omap: plane zpos/zorder management improvements

[Peter Ujfalusi <peter.ujfalusi@ti.com>]

Use the plane index as default zpos for all planes. Even if the
application is not setting zpos/zorder explicitly we will have unique zpos
for each plane.

Planes with identical zpos value will result undefined behavior:
disappearing planes, screen flickering and it is not supported by the
hardware.

Enforce that all planes must have unique zpos on the given crtc by
returning error when duplicate zpos value is requested.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
---
Hi,

Changes since v4:
- further simplify the zpos checking by using a mask and a single loop
- Commit message has been extended

Changes since v3:
- Use drm_plane_index() instead of storing the same index wothin omap_plane
  struct
- Optimize the zpos validation loop so we avoid extra checks.

Changes since v2:
- The check for duplicate zpos is moved to omap_crtc

Changes since v1:
- Dropped the zpos normalization related patches
- New patch based on the discussion, see commit message.

Regards,
Peter

 drivers/gpu/drm/omapdrm/omap_crtc.c  | 23 ++++++++++++++++++++++-
 drivers/gpu/drm/omapdrm/omap_plane.c | 15 ++++-----------
 2 files changed, 26 insertions(+), 12 deletions(-)

diff --git a/drivers/gpu/drm/omapdrm/omap_crtc.c b/drivers/gpu/drm/omapdrm/omap_crtc.c
index 1b8154e58d18..941a6440fc8e 100644
--- a/drivers/gpu/drm/omapdrm/omap_crtc.c
+++ b/drivers/gpu/drm/omapdrm/omap_crtc.c
@@ -486,6 +486,27 @@ static void omap_crtc_mode_set_nofb(struct drm_crtc *crtc)
 	}
 }
 
+static int omap_crtc_validate_zpos(struct drm_crtc *crtc,
+				   struct drm_crtc_state *state)
+{
+	struct drm_plane *plane;
+	const struct drm_plane_state *pstate;
+	unsigned int zpos_mask = 0;
+
+	/* Check the crts's planes against duplicated zpos value */
+	drm_atomic_crtc_state_for_each_plane_state(plane, pstate, state) {
+		if (zpos_mask & BIT(pstate->zpos)) {
+			DBG("crtc%u: zpos must be unique (zpos: %u)",
+			    crtc->index, pstate->zpos);
+			return -EINVAL;
+		}
+
+		zpos_mask |= BIT(pstate->zpos);
+	}
+
+	return 0;
+}
+
 static int omap_crtc_atomic_check(struct drm_crtc *crtc,
 				struct drm_crtc_state *state)
 {
@@ -509,7 +530,7 @@ static int omap_crtc_atomic_check(struct drm_crtc *crtc,
 		omap_crtc_state->rotation = pri_state->rotation;
 	}
 
-	return 0;
+	return omap_crtc_validate_zpos(crtc, state);
 }
 
 static void omap_crtc_atomic_begin(struct drm_crtc *crtc,
diff --git a/drivers/gpu/drm/omapdrm/omap_plane.c b/drivers/gpu/drm/omapdrm/omap_plane.c
index 7d789d1551a1..39f25210bef1 100644
--- a/drivers/gpu/drm/omapdrm/omap_plane.c
+++ b/drivers/gpu/drm/omapdrm/omap_plane.c
@@ -97,8 +97,7 @@ static void omap_plane_atomic_disable(struct drm_plane *plane,
 	struct omap_plane *omap_plane = to_omap_plane(plane);
 
 	plane->state->rotation = DRM_MODE_ROTATE_0;
-	plane->state->zpos = plane->type == DRM_PLANE_TYPE_PRIMARY
-			   ? 0 : omap_plane->id;
+	plane->state->zpos = drm_plane_index(plane);
 
 	priv->dispc_ops->ovl_enable(omap_plane->id, false);
 }
@@ -184,18 +183,12 @@ void omap_plane_install_properties(struct drm_plane *plane,
 
 static void omap_plane_reset(struct drm_plane *plane)
 {
-	struct omap_plane *omap_plane = to_omap_plane(plane);
-
 	drm_atomic_helper_plane_reset(plane);
 	if (!plane->state)
 		return;
 
-	/*
-	 * Set the zpos default depending on whether we are a primary or overlay
-	 * plane.
-	 */
-	plane->state->zpos = plane->type == DRM_PLANE_TYPE_PRIMARY
-			   ? 0 : omap_plane->id;
+	/* Set the zpos to the plane index. */
+	plane->state->zpos = drm_plane_index(plane);
 }
 
 static int omap_plane_atomic_set_property(struct drm_plane *plane,
@@ -295,7 +288,7 @@ struct drm_plane *omap_plane_init(struct drm_device *dev,
 	drm_plane_helper_add(plane, &omap_plane_helper_funcs);
 
 	omap_plane_install_properties(plane, &plane->base);
-	drm_plane_create_zpos_property(plane, 0, 0, num_planes - 1);
+	drm_plane_create_zpos_property(plane, idx, 0, num_planes - 1);
 
 	return plane;
 
-- 
Peter

Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki

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