drm/imx: imx-ldb: Add DDC support

Add support for reading EDID over Display Data Channel. If no DDC
adapter is available, falls back to hardcoded EDID or display-timings
node as before.

Signed-off-by: Steve Longerbeam <steve_longerbeam@mentor.com>
Signed-off-by: Akshay Bhat <akshay.bhat@timesys.com>
Acked-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

diff --git a/drivers/gpu/drm/imx/imx-ldb.c b/drivers/gpu/drm/imx/imx-ldb.c
index a58eee59550ab43d058dd64cc85ba43ea753a1dd..f506e8dd76cb4de1bfc13aaeaaf34055d3dc0325 100644 (file)
--- a/drivers/gpu/drm/imx/imx-ldb.c
+++ b/drivers/gpu/drm/imx/imx-ldb.c
@@ -59,6 +59,7 @@ struct imx_ldb_channel {
        struct drm_encoder encoder;
        struct drm_panel *panel;
        struct device_node *child;
+       struct i2c_adapter *ddc;
        int chno;
        void *edid;
        int edid_len;
@@ -107,6 +108,9 @@ static int imx_ldb_connector_get_modes(struct drm_connector *connector)
                        return num_modes;
        }
 
+       if (!imx_ldb_ch->edid && imx_ldb_ch->ddc)
+               imx_ldb_ch->edid = drm_get_edid(connector, imx_ldb_ch->ddc);
+
        if (imx_ldb_ch->edid) {
                drm_mode_connector_update_edid_property(connector,
                                                        imx_ldb_ch->edid);
@@ -553,6 +557,7 @@ 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 *ddc_node;
                struct device_node *port;
 
                ret = of_property_read_u32(child, "reg", &i);
@@ -595,14 +600,34 @@ static int imx_ldb_bind(struct device *dev, struct device *master, void *data)
                        }
                }
 
-               edidp = of_get_property(child, "edid", &channel->edid_len);
-               if (edidp) {
-                       channel->edid = kmemdup(edidp, channel->edid_len,
-                                               GFP_KERNEL);
-               } else if (!channel->panel) {
-                       ret = of_get_drm_display_mode(child, &channel->mode, 0);
-                       if (!ret)
-                               channel->mode_valid = 1;
+               ddc_node = of_parse_phandle(child, "ddc-i2c-bus", 0);
+               if (ddc_node) {
+                       channel->ddc = of_find_i2c_adapter_by_node(ddc_node);
+                       of_node_put(ddc_node);
+                       if (!channel->ddc) {
+                               dev_warn(dev, "failed to get ddc i2c adapter\n");
+                               return -EPROBE_DEFER;
+                       }
+               }
+
+               if (!channel->ddc) {
+                       /* if no DDC available, fallback to hardcoded EDID */
+                       dev_dbg(dev, "no ddc available\n");
+
+                       edidp = of_get_property(child, "edid",
+                                               &channel->edid_len);
+                       if (edidp) {
+                               channel->edid = kmemdup(edidp,
+                                                       channel->edid_len,
+                                                       GFP_KERNEL);
+                       } else if (!channel->panel) {
+                               /* fallback to display-timings node */
+                               ret = of_get_drm_display_mode(child,
+                                                             &channel->mode,
+                                                             0);
+                               if (!ret)
+                                       channel->mode_valid = 1;
+                       }
                }
 
                channel->bus_format = of_get_bus_format(dev, child);
@@ -647,6 +672,7 @@ static void imx_ldb_unbind(struct device *dev, struct device *master,
                channel->encoder.funcs->destroy(&channel->encoder);
 
                kfree(channel->edid);
+               i2c_put_adapter(channel->ddc);
        }
 }