[PATCH] drm/tidss: dispc: Rewrite naive plane positioning code

[Jyri Sarha]

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 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. This is easy since we have
access to the whole atomic state when updating the CRTC configuration.

Signed-off-by: Jyri Sarha <jsarha at ti.com>
---
 drivers/gpu/drm/tidss/tidss_crtc.c  |  2 +-
 drivers/gpu/drm/tidss/tidss_dispc.c | 66 ++++++++++++++++++++---------
 2 files changed, 47 insertions(+), 21 deletions(-)

diff --git a/drivers/gpu/drm/tidss/tidss_crtc.c b/drivers/gpu/drm/tidss/tidss_crtc.c
index 032c31ee2820..367efdebe2f8 100644
--- a/drivers/gpu/drm/tidss/tidss_crtc.c
+++ b/drivers/gpu/drm/tidss/tidss_crtc.c
@@ -143,7 +143,7 @@ static void tidss_crtc_atomic_flush(struct drm_crtc *crtc,
 	if (WARN_ON(!crtc->state->event))
 		return;
 
-	/* Write vp properties to HW if needed. */
+	/* Write vp properties and plane positions to HW if needed. */
 	dispc_vp_setup(tidss->dispc, tcrtc->hw_videoport, crtc->state, false);
 
 	WARN_ON(drm_crtc_vblank_get(crtc) != 0);
diff --git a/drivers/gpu/drm/tidss/tidss_dispc.c b/drivers/gpu/drm/tidss/tidss_dispc.c
index eeb160dc047b..cfc230d2a88a 100644
--- a/drivers/gpu/drm/tidss/tidss_dispc.c
+++ b/drivers/gpu/drm/tidss/tidss_dispc.c
@@ -20,6 +20,7 @@
 #include <linux/pm_runtime.h>
 #include <linux/regmap.h>
 
+#include <drm/drm_atomic.h>
 #include <drm/drm_fourcc.h>
 #include <drm/drm_fb_cma_helper.h>
 #include <drm/drm_gem_cma_helper.h>
@@ -281,11 +282,6 @@ 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 +303,6 @@ 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;
 
@@ -1301,13 +1295,54 @@ 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)
+static 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);
 }
 
+static void dispc_vp_position_planes(struct dispc_device *dispc,
+				     u32 hw_videoport,
+				     const struct drm_crtc_state *cstate,
+				     bool newmodeset)
+{
+	struct drm_device *ddev = &dispc->tidss->ddev;
+	int zpos;
+
+	if (!cstate->zpos_changed && !cstate->planes_changed && !newmodeset)
+		return;
+
+	for (zpos = 0; zpos < dispc->feat->num_planes; zpos++) {
+		struct drm_plane *plane;
+		bool zpos_taken = false;
+
+		drm_for_each_plane_mask(plane, ddev, cstate->plane_mask) {
+			if (WARN_ON(!plane->state))
+				continue;
+
+			if (plane->state->normalized_zpos == zpos) {
+				zpos_taken = true;
+				break;
+			}
+		}
+
+		if (zpos_taken) {
+			struct tidss_plane *tplane = to_tidss_plane(plane);
+			const struct drm_plane_state *pstate = plane->state;
+
+			dispc_ovr_set_plane(dispc, tplane->hw_plane_id,
+					    hw_videoport,
+					    pstate->crtc_x, pstate->crtc_y,
+					    zpos);
+		}
+		dispc_ovr_enable_layer(dispc, hw_videoport, zpos, zpos_taken);
+	}
+}
+
 /* CSC */
 enum csc_ctm {
 	CSC_RR, CSC_RG, CSC_RB,
@@ -2070,21 +2105,11 @@ 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;
@@ -2566,6 +2591,7 @@ void dispc_vp_setup(struct dispc_device *dispc, u32 hw_videoport,
 {
 	dispc_vp_set_default_color(dispc, hw_videoport, 0);
 	dispc_vp_set_color_mgmt(dispc, hw_videoport, state, newmodeset);
+	dispc_vp_position_planes(dispc, hw_videoport, state, newmodeset);
 }
 
 int dispc_runtime_suspend(struct dispc_device *dispc)
-- 
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