drm/dsi: Try to match non-DT DSI devices

Add a device name field in struct mipi_dsi_device. This name is not the
same as the device name (which is of the format "hostname.reg"). When
the device is created via DT, this name is set to the modalias string.
In the non-DT case, the driver creating the DSI device provides the
name by populating a field in struct mipi_dsi_device_info.

Matching for DT case would be as it was before. For the non-DT case, we
compare the device and driver names. Other buses (like I2C/SPI) perform
a non-DT match by comparing the device name and entries in the driver's
id_table. Such a mechanism isn't used for the DSI bus.

Reviewed-by: Andrzej Hajda <a.hajda@samsung.com>
Signed-off-by: Archit Taneja <architt@codeaurora.org>
Signed-off-by: Thierry Reding <treding@nvidia.com>

drivers/gpu/drm/drm_mipi_dsi.c

@@ -47,7 +47,17 @@
 
 static int mipi_dsi_device_match(struct device *dev, struct device_driver *drv)
 {
-	return of_driver_match_device(dev, drv);
+	struct mipi_dsi_device *dsi = to_mipi_dsi_device(dev);
+
+	/* attempt OF style match */
+	if (of_driver_match_device(dev, drv))
+		return 1;
+
+	/* compare DSI device and driver names */
+	if (!strcmp(dsi->name, drv->name))
+		return 1;
+
+	return 0;
 }
 
 static const struct dev_pm_ops mipi_dsi_device_pm_ops = {
@@ -138,6 +148,11 @@ of_mipi_dsi_device_add(struct mipi_dsi_host *host, struct device_node *node)
 	int ret;
 	u32 reg;
 
+	if (of_modalias_node(node, info.type, sizeof(info.type)) < 0) {
+		dev_err(dev, "modalias failure on %s\n", node->full_name);
+		return ERR_PTR(-EINVAL);
+	}
+
 	ret = of_property_read_u32(node, "reg", &reg);
 	if (ret) {
 		dev_err(dev, "device node %s has no valid reg property: %d\n",
@@ -197,6 +212,7 @@ mipi_dsi_device_register_full(struct mipi_dsi_host *host,
 
 	dsi->dev.of_node = info->node;
 	dsi->channel = info->channel;
+	strlcpy(dsi->name, info->type, sizeof(dsi->name));
 
 	ret = mipi_dsi_device_add(dsi);
 	if (ret) {