drm/tidss: dispc: Fix broken plane positioning code

The old implementation of placing planes on the CRTC while configuring
the planes was naive and relied on the order in which the planes were
configured, enabled, and disabled. The situation where a plane's zpos
was changed on the fly was completely broken. The usual symptoms of
this problem was scrambled display and a flood of sync lost errors,
when a plane was active in two layers at the same time, or a missing
plane, in case when a layer was accidentally disabled.

The rewrite takes a more straight forward approach when HW is
concerned. The plane positioning registers are in the CRTC (or
actually OVR) register space and it is more natural to configure them
in a one go when configuring the CRTC. To do this we need make sure we
have all the planes on the updated CRTCs in the new atomic state. The
untouched planes on CRTCs that need plane position update are added to
the atomic state in tidss_atomic_check().

Signed-off-by: Jyri Sarha <jsarha@ti.com>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200227120052.23168-1-jsarha@ti.com

1 files changed, 55 insertions, 0 deletions

diff --git a/drivers/gpu/drm/tidss/tidss_crtc.c b/drivers/gpu/drm/tidss/tidss_crtc.c
index 032c31ee2820..d4ce9bab8c7e 100644
--- a/drivers/gpu/drm/tidss/tidss_crtc.c
+++ b/drivers/gpu/drm/tidss/tidss_crtc.c
@@ -17,6 +17,7 @@
 #include "tidss_dispc.h"
 #include "tidss_drv.h"
 #include "tidss_irq.h"
+#include "tidss_plane.h"
 
 /* Page flip and frame done IRQs */
 
@@ -111,6 +112,54 @@ static int tidss_crtc_atomic_check(struct drm_crtc *crtc,
 	return dispc_vp_bus_check(dispc, hw_videoport, state);
 }
 
+/*
+ * This needs all affected planes to be present in the atomic
+ * state. The untouched planes are added to the state in
+ * tidss_atomic_check().
+ */
+static void tidss_crtc_position_planes(struct tidss_device *tidss,
+				       struct drm_crtc *crtc,
+				       struct drm_crtc_state *old_state,
+				       bool newmodeset)
+{
+	struct drm_atomic_state *ostate = old_state->state;
+	struct tidss_crtc *tcrtc = to_tidss_crtc(crtc);
+	struct drm_crtc_state *cstate = crtc->state;
+	int layer;
+
+	if (!newmodeset && !cstate->zpos_changed &&
+	    !to_tidss_crtc_state(cstate)->plane_pos_changed)
+		return;
+
+	for (layer = 0; layer < tidss->feat->num_planes; layer++) {
+		struct drm_plane_state *pstate;
+		struct drm_plane *plane;
+		bool layer_active = false;
+		int i;
+
+		for_each_new_plane_in_state(ostate, plane, pstate, i) {
+			if (pstate->crtc != crtc || !pstate->visible)
+				continue;
+
+			if (pstate->normalized_zpos == layer) {
+				layer_active = true;
+				break;
+			}
+		}
+
+		if (layer_active) {
+			struct tidss_plane *tplane = to_tidss_plane(plane);
+
+			dispc_ovr_set_plane(tidss->dispc, tplane->hw_plane_id,
+					    tcrtc->hw_videoport,
+					    pstate->crtc_x, pstate->crtc_y,
+					    layer);
+		}
+		dispc_ovr_enable_layer(tidss->dispc, tcrtc->hw_videoport, layer,
+				       layer_active);
+	}
+}
+
 static void tidss_crtc_atomic_flush(struct drm_crtc *crtc,
 				    struct drm_crtc_state *old_crtc_state)
 {
@@ -146,6 +195,9 @@ static void tidss_crtc_atomic_flush(struct drm_crtc *crtc,
 	/* Write vp properties to HW if needed. */
 	dispc_vp_setup(tidss->dispc, tcrtc->hw_videoport, crtc->state, false);
 
+	/* Update plane positions if needed. */
+	tidss_crtc_position_planes(tidss, crtc, old_crtc_state, false);
+
 	WARN_ON(drm_crtc_vblank_get(crtc) != 0);
 
 	spin_lock_irqsave(&ddev->event_lock, flags);
@@ -183,6 +235,7 @@ static void tidss_crtc_atomic_enable(struct drm_crtc *crtc,
 		return;
 
 	dispc_vp_setup(tidss->dispc, tcrtc->hw_videoport, crtc->state, true);
+	tidss_crtc_position_planes(tidss, crtc, old_state, true);
 
 	/* Turn vertical blanking interrupt reporting on. */
 	drm_crtc_vblank_on(crtc);
@@ -318,6 +371,8 @@ static struct drm_crtc_state *tidss_crtc_duplicate_state(struct drm_crtc *crtc)
 
 	__drm_atomic_helper_crtc_duplicate_state(crtc, &state->base);
 
+	state->plane_pos_changed = false;
+
 	state->bus_format = current_state->bus_format;
 	state->bus_flags = current_state->bus_flags;