drm/msm/dsi: Use a standard DT binding for data lanes

A more standard DT binding describing data lanes already exists here:
Documentation/devicetree/bindings/media/video-interfaces.txt

Use this binding instead of "qcom,data-lane-map". One difference
in the standard binding w.r.t to the existing binding is that it
provides a logical to physical mapping instead of the other way
round. Tweak the code to translate the data the way we want it.

The MSM DSI DT bindings aren't used anywhere at the moment, so
it's okay to update this property.
Signed-off-by: Archit Taneja <architt@codeaurora.org>
Signed-off-by: Rob Clark <robdclark@gmail.com>

drivers/gpu/drm/msm/dsi/dsi_host.c

@@ -1543,7 +1543,7 @@ static int dsi_host_parse_lane_data(struct msm_dsi_host *msm_host,
 	u32 lane_map[4];
 	int ret, i, len, num_lanes;
 
-	prop = of_find_property(ep, "qcom,data-lane-map", &len);
+	prop = of_find_property(ep, "data-lanes", &len);
 	if (!prop) {
 		dev_dbg(dev, "failed to find data lane mapping\n");
 		return -EINVAL;
@@ -1558,7 +1558,7 @@ static int dsi_host_parse_lane_data(struct msm_dsi_host *msm_host,
 
 	msm_host->num_data_lanes = num_lanes;
 
-	ret = of_property_read_u32_array(ep, "qcom,data-lane-map", lane_map,
+	ret = of_property_read_u32_array(ep, "data-lanes", lane_map,
 					 num_lanes);
 	if (ret) {
 		dev_err(dev, "failed to read lane data\n");
@@ -1573,8 +1573,19 @@ static int dsi_host_parse_lane_data(struct msm_dsi_host *msm_host,
 		const int *swap = supported_data_lane_swaps[i];
 		int j;
 
+		/*
+		 * the data-lanes array we get from DT has a logical->physical
+		 * mapping. The "data lane swap" register field represents
+		 * supported configurations in a physical->logical mapping.
+		 * Translate the DT mapping to what we understand and find a
+		 * configuration that works.
+		 */
 		for (j = 0; j < num_lanes; j++) {
-			if (swap[j] != lane_map[j])
+			if (lane_map[j] < 0 || lane_map[j] > 3)
+				dev_err(dev, "bad physical lane entry %u\n",
+					lane_map[j]);
+
+			if (swap[lane_map[j]] != j)
 				break;
 		}