[PATCH 49/72] imx-drm: imx-ldb: Add DDC support

[Steve Longerbeam]

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 at mentor.com>
---
 drivers/staging/imx-drm/imx-ldb.c |   39 +++++++++++++++++++++++++++++--------
 1 file changed, 31 insertions(+), 8 deletions(-)

diff --git a/drivers/staging/imx-drm/imx-ldb.c 
b/drivers/staging/imx-drm/imx-ldb.c
index 1eb632f..6c16cf2 100644
--- a/drivers/staging/imx-drm/imx-ldb.c
+++ b/drivers/staging/imx-drm/imx-ldb.c
@@ -61,6 +61,7 @@ struct imx_ldb_channel {
        struct drm_connector connector;
        struct drm_encoder encoder;
        struct device_node *child;
+       struct i2c_adapter *ddc;
        int chno;
        void *edid;
        int edid_len;
@@ -103,6 +104,9 @@ static int imx_ldb_connector_get_modes(struct drm_connector 
*connector)

        imx_ldb_entry_dbg(imx_ldb_ch);

+       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);
@@ -529,6 +533,7 @@ 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;

                ret = of_property_read_u32(child, "reg", &i);
                if (ret || i < 0 || i > 1)
@@ -547,14 +552,30 @@ static int imx_ldb_bind(struct device *dev, struct device 
*master, void *data)
                channel->chno = i;
                channel->child = child;

-               edidp = of_get_property(child, "edid", &channel->edid_len);
-               if (edidp) {
-                       channel->edid = kmemdup(edidp, channel->edid_len,
-                                               GFP_KERNEL);
-               } else {
-                       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) {
+                       /* 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 {
+                               /* fallback to display-timings node */
+                               ret = of_get_drm_display_mode(child,
+                                                             &channel->mode,
+                                                             0);
+                               if (!ret)
+                                       channel->mode_valid = 1;
+                       }
                }

                ret = of_property_read_u32(child, "fsl,data-width", &datawidth);
@@ -616,6 +637,8 @@ static void imx_ldb_unbind(struct device *dev, struct 
device *master,

                channel->connector.funcs->destroy(&channel->connector);
                channel->encoder.funcs->destroy(&channel->encoder);
+
+               i2c_put_adapter(channel->ddc);
        }
 }

-- 
1.7.9.5