drm/imx: imx-ldb: add drm_panel support

This patch allows to optionally attach the lvds-channel to a panel
supported by a drm_panel driver using of-graph bindings, instead of
supplying the modes via display-timings in the device tree.

This depends on of_graph_get_port_by_id and uses the OF graph to
link the optional DRM panel to the LDB lvds-channel. The output
port number is 1 on devices without the 4-port input multiplexer
(i.MX5) and 4 on devices with the mux (i.MX6).

Before:

	ldb {
		...

		lvds-channel@0 {
			...

			display-timings {
				native-timing = <&timing1>;
				timing1: etm0700g0dh6 {
					hactive = <800>;
					vactive = <480>;
					clock-frequency = <33260000>;
					hsync-len = <128>;
					hback-porch = <88>;
					hfront-porch = <40>;
					vsync-len = <2>;
					vback-porch = <33>;
					vfront-porch = <10>;
					hsync-active = <0>;
					vsync-active = <0>;
					...
				};
			};
			...
		};
	};

After:
	ldb {
		...

		lvds-channel@0 {
			...

			port@4 {
				reg = <4>;

				lvds_out: endpoint {
					remote_endpoint = <&panel_in>;
				};
			};
		};
	};

	panel {
		compatible = "edt,etm0700g0dh6", "simple-panel";
		...

		port {
			panel_in: endpoint {
				remote-endpoint = <&lvds_out>;
			};
		};
	};

[Fixed build error due to missing select on DRM_PANEL --rmk]
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

2 files changed, 47 insertions, 2 deletions

diff --git a/drivers/gpu/drm/imx/Kconfig b/drivers/gpu/drm/imx/Kconfig
index 33cdddf26684..2b81a417cf29 100644
--- a/drivers/gpu/drm/imx/Kconfig
+++ b/drivers/gpu/drm/imx/Kconfig
@@ -36,6 +36,7 @@ config DRM_IMX_TVE
 config DRM_IMX_LDB
         tristate "Support for LVDS displays"
         depends on DRM_IMX && MFD_SYSCON
+        select DRM_PANEL
         help
           Choose this to enable the internal LVDS Display Bridge (LDB)
           found on i.MX53 and i.MX6 processors.
diff --git a/drivers/gpu/drm/imx/imx-ldb.c b/drivers/gpu/drm/imx/imx-ldb.c
index cd062b11a102..4286399590c3 100644
--- a/drivers/gpu/drm/imx/imx-ldb.c
+++ b/drivers/gpu/drm/imx/imx-ldb.c
@@ -19,10 +19,11 @@
 #include <drm/drmP.h>
 #include <drm/drm_fb_helper.h>
 #include <drm/drm_crtc_helper.h>
+#include <drm/drm_panel.h>
 #include <linux/mfd/syscon.h>
 #include <linux/mfd/syscon/imx6q-iomuxc-gpr.h>
-#include <linux/of_address.h>
 #include <linux/of_device.h>
+#include <linux/of_graph.h>
 #include <video/of_videomode.h>
 #include <linux/regmap.h>
 #include <linux/videodev2.h>
@@ -55,6 +56,7 @@ struct imx_ldb_channel {
         struct imx_ldb *ldb;
         struct drm_connector connector;
         struct drm_encoder encoder;
+        struct drm_panel *panel;
         struct device_node *child;
         int chno;
         void *edid;
@@ -91,6 +93,13 @@ static int imx_ldb_connector_get_modes(struct drm_connector *connector)
         struct imx_ldb_channel *imx_ldb_ch = con_to_imx_ldb_ch(connector);
         int num_modes = 0;
 
+        if (imx_ldb_ch->panel && imx_ldb_ch->panel->funcs &&
+            imx_ldb_ch->panel->funcs->get_modes) {
+                num_modes = imx_ldb_ch->panel->funcs->get_modes(imx_ldb_ch->panel);
+                if (num_modes > 0)
+                        return num_modes;
+        }
+
         if (imx_ldb_ch->edid) {
                 drm_mode_connector_update_edid_property(connector,
                                                         imx_ldb_ch->edid);
@@ -190,6 +199,8 @@ static void imx_ldb_encoder_commit(struct drm_encoder *encoder)
         int dual = ldb->ldb_ctrl & LDB_SPLIT_MODE_EN;
         int mux = imx_drm_encoder_get_mux_id(imx_ldb_ch->child, encoder);
 
+        drm_panel_prepare(imx_ldb_ch->panel);
+
         if (dual) {
                 clk_prepare_enable(ldb->clk[0]);
                 clk_prepare_enable(ldb->clk[1]);
@@ -223,6 +234,8 @@ static void imx_ldb_encoder_commit(struct drm_encoder *encoder)
         }
 
         regmap_write(ldb->regmap, IOMUXC_GPR2, ldb->ldb_ctrl);
+
+        drm_panel_enable(imx_ldb_ch->panel);
 }
 
 static void imx_ldb_encoder_mode_set(struct drm_encoder *encoder,
@@ -287,6 +300,8 @@ static void imx_ldb_encoder_disable(struct drm_encoder *encoder)
                  (ldb->ldb_ctrl & LDB_CH1_MODE_EN_MASK) == 0)
                 return;
 
+        drm_panel_disable(imx_ldb_ch->panel);
+
         if (imx_ldb_ch == &ldb->channel[0])
                 ldb->ldb_ctrl &= ~LDB_CH0_MODE_EN_MASK;
         else if (imx_ldb_ch == &ldb->channel[1])
@@ -298,6 +313,8 @@ static void imx_ldb_encoder_disable(struct drm_encoder *encoder)
                 clk_disable_unprepare(ldb->clk[0]);
                 clk_disable_unprepare(ldb->clk[1]);
         }
+
+        drm_panel_unprepare(imx_ldb_ch->panel);
 }
 
 static struct drm_connector_funcs imx_ldb_connector_funcs = {
@@ -371,6 +388,9 @@ static int imx_ldb_register(struct drm_device *drm,
         drm_connector_init(drm, &imx_ldb_ch->connector,
                            &imx_ldb_connector_funcs, DRM_MODE_CONNECTOR_LVDS);
 
+        if (imx_ldb_ch->panel)
+                drm_panel_attach(imx_ldb_ch->panel, &imx_ldb_ch->connector);
+
         drm_mode_connector_attach_encoder(&imx_ldb_ch->connector,
                         &imx_ldb_ch->encoder);
 
@@ -485,6 +505,7 @@ static int imx_ldb_bind(struct device *dev, struct device *master, void *data)
 
         for_each_child_of_node(np, child) {
                 struct imx_ldb_channel *channel;
+                struct device_node *port;
 
                 ret = of_property_read_u32(child, "reg", &i);
                 if (ret || i < 0 || i > 1)
@@ -503,11 +524,34 @@ static int imx_ldb_bind(struct device *dev, struct device *master, void *data)
                 channel->chno = i;
                 channel->child = child;
 
+                /*
+                 * The output port is port@4 with an external 4-port mux or
+                 * port@2 with the internal 2-port mux.
+                 */
+                port = of_graph_get_port_by_id(child, imx_ldb->lvds_mux ? 4 : 2);
+                if (port) {
+                        struct device_node *endpoint, *remote;
+
+                        endpoint = of_get_child_by_name(port, "endpoint");
+                        if (endpoint) {
+                                remote = of_graph_get_remote_port_parent(endpoint);
+                                if (remote)
+                                        channel->panel = of_drm_find_panel(remote);
+                                else
+                                        return -EPROBE_DEFER;
+                                if (!channel->panel) {
+                                        dev_err(dev, "panel not found: %s\n",
+                                                remote->full_name);
+                                        return -EPROBE_DEFER;
+                                }
+                        }
+                }
+
                 edidp = of_get_property(child, "edid", &channel->edid_len);
                 if (edidp) {
                         channel->edid = kmemdup(edidp, channel->edid_len,
                                                 GFP_KERNEL);
-                } else {
+                } else if (!channel->panel) {
                         ret = of_get_drm_display_mode(child, &channel->mode, 0);
                         if (!ret)
                                 channel->mode_valid = 1;