[PATCH] drm/imx: parallel-display: fix drm_panel support

[Philipp Zabel]

The parallel-display driver used an undocumented, non-standard property
"fsl,panel" to optionally associate with a drm_panel device. This patch
fixes the driver to use the same OF graph bindings as the LDB driver
instead:

    parallel-display {
            compatible = "fsl,imx-parallel-display";
            ...

            port at 1 {
                    reg = <1>;

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

    panel {
            ...

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

Signed-off-by: Philipp Zabel <p.zabel at pengutronix.de>
---
 .../devicetree/bindings/drm/imx/fsl-imx-drm.txt    | 26 ++++++++++++++++++++--
 drivers/gpu/drm/imx/parallel-display.c             | 21 ++++++++++++-----
 2 files changed, 39 insertions(+), 8 deletions(-)

diff --git a/Documentation/devicetree/bindings/drm/imx/fsl-imx-drm.txt 
b/Documentation/devicetree/bindings/drm/imx/fsl-imx-drm.txt
index f349703..29c0467 100644
--- a/Documentation/devicetree/bindings/drm/imx/fsl-imx-drm.txt
+++ b/Documentation/devicetree/bindings/drm/imx/fsl-imx-drm.txt
@@ -65,8 +65,10 @@ Optional properties:
 - edid: verbatim EDID data block describing attached display.
 - ddc: phandle describing the i2c bus handling the display data
   channel
-- port: A port node with endpoint definitions as defined in
+- port@[0-1]: Port nodes with endpoint definitions as defined in
   Documentation/devicetree/bindings/media/video-interfaces.txt.
+  Port 0 is the input port connected to the IPU display interface,
+  port 1 is the output port connected to a panel.

 example:

@@ -75,9 +77,29 @@ display at di0 {
        edid = [edid-data];
        interface-pix-fmt = "rgb24";

-       port {
+       port at 0 {
+               reg = <0>;
+
                display_in: endpoint {
                        remote-endpoint = <&ipu_di0_disp0>;
                };
        };
+
+       port at 1 {
+               reg = <1>;
+
+               display_out: endpoint {
+                       remote-endpoint = <&panel_in>;
+               };
+       };
+};
+
+panel {
+       ...
+
+       port {
+               panel_in: endpoint {
+                       remote-endpoint = <&display_out>;
+               };
+       };
 };
diff --git a/drivers/gpu/drm/imx/parallel-display.c 
b/drivers/gpu/drm/imx/parallel-display.c
index 78db5d4..c663099 100644
--- a/drivers/gpu/drm/imx/parallel-display.c
+++ b/drivers/gpu/drm/imx/parallel-display.c
@@ -21,6 +21,7 @@
 #include <drm/drm_panel.h>
 #include <linux/videodev2.h>
 #include <video/of_display_timing.h>
+#include <linux/of_graph.h>

 #include "imx-drm.h"

@@ -216,7 +217,7 @@ static int imx_pd_bind(struct device *dev, struct device 
*master, void *data)
 {
        struct drm_device *drm = data;
        struct device_node *np = dev->of_node;
-       struct device_node *panel_node;
+       struct device_node *port;
        const u8 *edidp;
        struct imx_parallel_display *imxpd;
        int ret;
@@ -245,11 +246,19 @@ static int imx_pd_bind(struct device *dev, struct device 
*master, void *data)
                        imxpd->interface_pix_fmt = V4L2_PIX_FMT_BGR24;
        }

-       panel_node = of_parse_phandle(np, "fsl,panel", 0);
-       if (panel_node) {
-               imxpd->panel = of_drm_find_panel(panel_node);
-               if (!imxpd->panel)
-                       return -EPROBE_DEFER;
+       /* port at 1 is the output port */
+       port = of_graph_get_port_by_id(np, 1);
+       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)
+                               imxpd->panel = of_drm_find_panel(remote);
+                       if (!imxpd->panel)
+                               return -EPROBE_DEFER;
+               }
        }

        imxpd->dev = dev;
-- 
2.1.4