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

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;
 

drivers/gpu/drm/tidss/tidss_crtc.h

@@ -32,6 +32,8 @@ struct tidss_crtc_state {
 	/* Must be first. */
 	struct drm_crtc_state base;
 
+	bool plane_pos_changed;
+
 	u32 bus_format;
 	u32 bus_flags;
 };

drivers/gpu/drm/tidss/tidss_dispc.c

@@ -281,11 +281,6 @@ struct dss_vp_data {
 	u32 *gamma_table;
 };
 
-struct dss_plane_data {
-	u32 zorder;
-	u32 hw_videoport;
-};
-
 struct dispc_device {
 	struct tidss_device *tidss;
 	struct device *dev;
@@ -307,8 +302,6 @@ struct dispc_device {
 
 	struct dss_vp_data vp_data[TIDSS_MAX_PORTS];
 
-	struct dss_plane_data plane_data[TIDSS_MAX_PLANES];
-
 	u32 *fourccs;
 	u32 num_fourccs;
 
@@ -1247,7 +1240,7 @@ int dispc_vp_set_clk_rate(struct dispc_device *dispc, u32 hw_videoport,
 /* OVR */
 static void dispc_k2g_ovr_set_plane(struct dispc_device *dispc,
 				    u32 hw_plane, u32 hw_videoport,
-				    u32 x, u32 y, u32 zpos)
+				    u32 x, u32 y, u32 layer)
 {
 	/* On k2g there is only one plane and no need for ovr */
 	dispc_vid_write(dispc, hw_plane, DISPC_VID_K2G_POSITION,
@@ -1256,44 +1249,43 @@ static void dispc_k2g_ovr_set_plane(struct dispc_device *dispc,
 
 static void dispc_am65x_ovr_set_plane(struct dispc_device *dispc,
 				      u32 hw_plane, u32 hw_videoport,
-				      u32 x, u32 y, u32 zpos)
+				      u32 x, u32 y, u32 layer)
 {
-	OVR_REG_FLD_MOD(dispc, hw_videoport, DISPC_OVR_ATTRIBUTES(zpos),
+	OVR_REG_FLD_MOD(dispc, hw_videoport, DISPC_OVR_ATTRIBUTES(layer),
 			hw_plane, 4, 1);
-	OVR_REG_FLD_MOD(dispc, hw_videoport, DISPC_OVR_ATTRIBUTES(zpos),
+	OVR_REG_FLD_MOD(dispc, hw_videoport, DISPC_OVR_ATTRIBUTES(layer),
 			x, 17, 6);
-	OVR_REG_FLD_MOD(dispc, hw_videoport, DISPC_OVR_ATTRIBUTES(zpos),
+	OVR_REG_FLD_MOD(dispc, hw_videoport, DISPC_OVR_ATTRIBUTES(layer),
 			y, 30, 19);
 }
 
 static void dispc_j721e_ovr_set_plane(struct dispc_device *dispc,
 				      u32 hw_plane, u32 hw_videoport,
-				      u32 x, u32 y, u32 zpos)
+				      u32 x, u32 y, u32 layer)
 {
-	OVR_REG_FLD_MOD(dispc, hw_videoport, DISPC_OVR_ATTRIBUTES(zpos),
+	OVR_REG_FLD_MOD(dispc, hw_videoport, DISPC_OVR_ATTRIBUTES(layer),
 			hw_plane, 4, 1);
-	OVR_REG_FLD_MOD(dispc, hw_videoport, DISPC_OVR_ATTRIBUTES2(zpos),
+	OVR_REG_FLD_MOD(dispc, hw_videoport, DISPC_OVR_ATTRIBUTES2(layer),
 			x, 13, 0);
-	OVR_REG_FLD_MOD(dispc, hw_videoport, DISPC_OVR_ATTRIBUTES2(zpos),
+	OVR_REG_FLD_MOD(dispc, hw_videoport, DISPC_OVR_ATTRIBUTES2(layer),
 			y, 29, 16);
 }
 
-static void dispc_ovr_set_plane(struct dispc_device *dispc,
-				u32 hw_plane, u32 hw_videoport,
-				u32 x, u32 y, u32 zpos)
+void dispc_ovr_set_plane(struct dispc_device *dispc, u32 hw_plane,
+			 u32 hw_videoport, u32 x, u32 y, u32 layer)
 {
 	switch (dispc->feat->subrev) {
 	case DISPC_K2G:
 		dispc_k2g_ovr_set_plane(dispc, hw_plane, hw_videoport,
-					x, y, zpos);
+					x, y, layer);
 		break;
 	case DISPC_AM65X:
 		dispc_am65x_ovr_set_plane(dispc, hw_plane, hw_videoport,
-					  x, y, zpos);
+					  x, y, layer);
 		break;
 	case DISPC_J721E:
 		dispc_j721e_ovr_set_plane(dispc, hw_plane, hw_videoport,
-					  x, y, zpos);
+					  x, y, layer);
 		break;
 	default:
 		WARN_ON(1);
@@ -1301,10 +1293,13 @@ static void dispc_ovr_set_plane(struct dispc_device *dispc,
 	}
 }
 
-static void dispc_ovr_enable_plane(struct dispc_device *dispc,
-				   u32 hw_videoport, u32 zpos, bool enable)
+void dispc_ovr_enable_layer(struct dispc_device *dispc,
+			    u32 hw_videoport, u32 layer, bool enable)
 {
-	OVR_REG_FLD_MOD(dispc, hw_videoport, DISPC_OVR_ATTRIBUTES(zpos),
+	if (dispc->feat->subrev == DISPC_K2G)
+		return;
+
+	OVR_REG_FLD_MOD(dispc, hw_videoport, DISPC_OVR_ATTRIBUTES(layer),
 			!!enable, 0, 0);
 }
 
@@ -2070,21 +2065,11 @@ int dispc_plane_setup(struct dispc_device *dispc, u32 hw_plane,
 		VID_REG_FLD_MOD(dispc, hw_plane, DISPC_VID_ATTRIBUTES, 0,
 				28, 28);
 
-	dispc_ovr_set_plane(dispc, hw_plane, hw_videoport,
-			    state->crtc_x, state->crtc_y,
-			    state->normalized_zpos);
-
-	dispc->plane_data[hw_plane].zorder = state->normalized_zpos;
-	dispc->plane_data[hw_plane].hw_videoport = hw_videoport;
-
 	return 0;
 }
 
 int dispc_plane_enable(struct dispc_device *dispc, u32 hw_plane, bool enable)
 {
-	dispc_ovr_enable_plane(dispc, dispc->plane_data[hw_plane].hw_videoport,
-			       dispc->plane_data[hw_plane].zorder, enable);
-
 	VID_REG_FLD_MOD(dispc, hw_plane, DISPC_VID_ATTRIBUTES, !!enable, 0, 0);
 
 	return 0;

drivers/gpu/drm/tidss/tidss_dispc.h

@@ -94,6 +94,11 @@ extern const struct dispc_features dispc_j721e_feats;
 void dispc_set_irqenable(struct dispc_device *dispc, dispc_irq_t mask);
 dispc_irq_t dispc_read_and_clear_irqstatus(struct dispc_device *dispc);
 
+void dispc_ovr_set_plane(struct dispc_device *dispc, u32 hw_plane,
+			 u32 hw_videoport, u32 x, u32 y, u32 layer);
+void dispc_ovr_enable_layer(struct dispc_device *dispc,
+			    u32 hw_videoport, u32 layer, bool enable);
+
 void dispc_vp_prepare(struct dispc_device *dispc, u32 hw_videoport,
 		      const struct drm_crtc_state *state);
 void dispc_vp_enable(struct dispc_device *dispc, u32 hw_videoport,

drivers/gpu/drm/tidss/tidss_kms.c

@@ -47,9 +47,59 @@ static const struct drm_mode_config_helper_funcs mode_config_helper_funcs = {
 	.atomic_commit_tail = tidss_atomic_commit_tail,
 };
 
+static int tidss_atomic_check(struct drm_device *ddev,
+			      struct drm_atomic_state *state)
+{
+	struct drm_plane_state *opstate;
+	struct drm_plane_state *npstate;
+	struct drm_plane *plane;
+	struct drm_crtc_state *cstate;
+	struct drm_crtc *crtc;
+	int ret, i;
+
+	ret = drm_atomic_helper_check(ddev, state);
+	if (ret)
+		return ret;
+
+	/*
+	 * Add all active planes on a CRTC to the atomic state, if
+	 * x/y/z position or activity of any plane on that CRTC
+	 * changes. This is needed for updating the plane positions in
+	 * tidss_crtc_position_planes() which is called from
+	 * crtc_atomic_enable() and crtc_atomic_flush(). We have an
+	 * extra flag to to mark x,y-position changes and together
+	 * with zpos_changed the condition recognizes all the above
+	 * cases.
+	 */
+	for_each_oldnew_plane_in_state(state, plane, opstate, npstate, i) {
+		if (!npstate->crtc || !npstate->visible)
+			continue;
+
+		if (!opstate->crtc || opstate->crtc_x != npstate->crtc_x ||
+		    opstate->crtc_y != npstate->crtc_y) {
+			cstate = drm_atomic_get_crtc_state(state,
+							   npstate->crtc);
+			if (IS_ERR(cstate))
+				return PTR_ERR(cstate);
+			to_tidss_crtc_state(cstate)->plane_pos_changed = true;
+		}
+	}
+
+	for_each_new_crtc_in_state(state, crtc, cstate, i) {
+		if (to_tidss_crtc_state(cstate)->plane_pos_changed ||
+		    cstate->zpos_changed) {
+			ret = drm_atomic_add_affected_planes(state, crtc);
+			if (ret)
+				return ret;
+		}
+	}
+
+	return 0;
+}
+
 static const struct drm_mode_config_funcs mode_config_funcs = {
 	.fb_create = drm_gem_fb_create,
-	.atomic_check = drm_atomic_helper_check,
+	.atomic_check = tidss_atomic_check,
 	.atomic_commit = drm_atomic_helper_commit,
 };