[PATCH 2/3] drm/vc4: Take underscan setup into account when updating planes

[Boris Brezillon]

Applying an underscan setup is just a matter of scaling all planes
appropriately and adjusting the CRTC X/Y offset to account for the
horizontal and vertical border.

Create an vc4_plane_underscan_adj() function doing that and call it from
vc4_plane_setup_clipping_and_scaling() so that we are ready to attach
underscan properties to the HDMI connector.

Signed-off-by: Boris Brezillon <boris.brezillon at bootlin.com>
---
 drivers/gpu/drm/vc4/vc4_plane.c | 49 ++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 48 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/vc4/vc4_plane.c b/drivers/gpu/drm/vc4/vc4_plane.c
index 71d44c357d35..7d5667b1f990 100644
--- a/drivers/gpu/drm/vc4/vc4_plane.c
+++ b/drivers/gpu/drm/vc4/vc4_plane.c
@@ -258,6 +258,49 @@ static u32 vc4_get_scl_field(struct drm_plane_state *state, int plane)
 	}
 }
 
+static int vc4_plane_underscan_adj(struct drm_plane_state *pstate)
+{
+	struct vc4_plane_state *vc4_pstate = to_vc4_plane_state(pstate);
+	struct drm_connector_state *conn_state = NULL;
+	struct drm_connector *conn;
+	struct drm_crtc_state *crtc_state;
+	int i;
+
+	for_each_new_connector_in_state(pstate->state, conn, conn_state, i) {
+		if (conn_state->crtc == pstate->crtc)
+			break;
+	}
+
+	if (i == pstate->state->num_connector)
+		return 0;
+
+	if (conn_state->underscan.mode != DRM_UNDERSCAN_ON)
+		return 0;
+
+	crtc_state = drm_atomic_get_new_crtc_state(pstate->state,
+						   pstate->crtc);
+
+	if (conn_state->underscan.hborder >= crtc_state->mode.hdisplay ||
+	    conn_state->underscan.vborder >= crtc_state->mode.vdisplay)
+		return -EINVAL;
+
+	vc4_pstate->crtc_x += conn_state->underscan.hborder / 2;
+	vc4_pstate->crtc_y += conn_state->underscan.vborder / 2;
+	vc4_pstate->crtc_w = (vc4_pstate->crtc_w *
+			      (crtc_state->mode.hdisplay -
+			       conn_state->underscan.hborder)) /
+			     crtc_state->mode.hdisplay;
+	vc4_pstate->crtc_h = (vc4_pstate->crtc_h *
+			      (crtc_state->mode.vdisplay -
+			       conn_state->underscan.vborder)) /
+			     crtc_state->mode.vdisplay;
+
+	if (!vc4_pstate->crtc_w || !vc4_pstate->crtc_h)
+		return -EINVAL;
+
+	return 0;
+}
+
 static int vc4_plane_setup_clipping_and_scaling(struct drm_plane_state *state)
 {
 	struct drm_plane *plane = state->plane;
@@ -269,7 +312,7 @@ static int vc4_plane_setup_clipping_and_scaling(struct drm_plane_state *state)
 	int num_planes = fb->format->num_planes;
 	u32 h_subsample = 1;
 	u32 v_subsample = 1;
-	int i;
+	int i, ret;
 
 	for (i = 0; i < num_planes; i++)
 		vc4_state->offsets[i] = bo->paddr + fb->offsets[i];
@@ -292,6 +335,10 @@ static int vc4_plane_setup_clipping_and_scaling(struct drm_plane_state *state)
 	vc4_state->crtc_w = state->crtc_w;
 	vc4_state->crtc_h = state->crtc_h;
 
+	ret = vc4_plane_underscan_adj(state);
+	if (ret)
+		return ret;
+
 	vc4_state->x_scaling[0] = vc4_get_scaling_mode(vc4_state->src_w[0],
 						       vc4_state->crtc_w);
 	vc4_state->y_scaling[0] = vc4_get_scaling_mode(vc4_state->src_h[0],
-- 
2.14.1