drm: platform multi-device support

Include the device id in the bus-id to give userspace a way to open
the correct "cardN" when there are multiple device instances.

Signed-off-by: Rob Clark <rob@ti.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/drm_platform.c

@@ -123,14 +123,15 @@ static int drm_platform_set_busid(struct drm_device *dev, struct drm_master *mas
 {
 	int len, ret;
 
-	master->unique_len = 10 + strlen(dev->platformdev->name);
+	master->unique_len = 13 + strlen(dev->platformdev->name);
+	master->unique_size = master->unique_len;
 	master->unique = kmalloc(master->unique_len + 1, GFP_KERNEL);
 
 	if (master->unique == NULL)
 		return -ENOMEM;
 
 	len = snprintf(master->unique, master->unique_len,
-		       "platform:%s", dev->platformdev->name);
+			"platform:%s:%02d", dev->platformdev->name, dev->platformdev->id);
 
 	if (len > master->unique_len) {
 		DRM_ERROR("Unique buffer overflowed\n");