drm/rockchip: dw_hdmi_qp: expose "overscan" property

Expose the "overscan" connector property as recognized by KWin and the
likes to compensate for TV overscan cropping.

The CRTC will use the margin values derived from this overscan percentage
in its post-composition scaler to add appropriate blank margins on all
sides of the output image so that the TV doesn't eat up visible content.

Signed-off-by: Alexey Charkov <alchark@flipper.net>

Author: alchark

drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c

@@ -158,13 +158,21 @@ dw_hdmi_qp_rockchip_encoder_atomic_check(struct drm_encoder *encoder,
 					 struct drm_connector_state *conn_state)
 {
 	const struct drm_display_info *info = &conn_state->connector->display_info;
+	const struct drm_display_mode *adj_mode = &crtc_state->adjusted_mode;
 	struct rockchip_crtc_state *s = to_rockchip_crtc_state(crtc_state);
 	struct rockchip_hdmi_qp *hdmi = to_rockchip_hdmi_qp(encoder);
 	struct dw_hdmi_qp_link_cfg *lcfg = &hdmi->link_cfg;
 	union phy_configure_opts phy_cfg = {};
+	unsigned int overscan;
 	enum phy_hdmi_mode mode;
 	int ret;
 
+	overscan = min(conn_state->tv.overscan, 100u);
+	s->tv_margins.left   = adj_mode->hdisplay * overscan / 200;
+	s->tv_margins.right  = s->tv_margins.left;
+	s->tv_margins.top    = adj_mode->vdisplay * overscan / 200;
+	s->tv_margins.bottom = s->tv_margins.top;
+
 	if (lcfg->tmds_char_rate == conn_state->hdmi.tmds_char_rate &&
 	    s->output_bpc == conn_state->hdmi.output_bpc)
 		return 0;
@@ -768,6 +776,14 @@ static int dw_hdmi_qp_rockchip_bind(struct device *dev, struct device *master,
 		return dev_err_probe(dev, PTR_ERR(hdmi->connector),
 				     "Failed to init bridge connector\n");
 
+	ret = drm_mode_create_tv_properties_legacy(drm, 0, NULL);
+	if (ret)
+		return dev_err_probe(dev, ret,
+				     "Failed to create TV connector properties\n");
+
+	drm_object_attach_property(&hdmi->connector->base,
+				   drm->mode_config.tv_overscan_property, 0);
+
 	ret = drm_connector_attach_encoder(hdmi->connector, encoder);
 	if (ret)
 		return dev_err_probe(dev, ret, "Failed to attach connector\n");