drm/fb-helper: Add module option to disable fbdev emulation

[firefly-linux-kernel-4.4.55.git] / drivers / gpu / drm / drm_fb_helper.c

diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
index 418d299f3b129b307f86a970fdf49d3a826af4c8..ba12f51f106f283bbe110cb8a1114c52b157fdb0 100644 (file)
--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -39,6 +39,11 @@
 #include <drm/drm_fb_helper.h>
 #include <drm/drm_crtc_helper.h>
 
+static bool drm_fbdev_emulation = true;
+module_param_named(fbdev_emulation, drm_fbdev_emulation, bool, 0600);
+MODULE_PARM_DESC(fbdev_emulation,
+                "Enable legacy fbdev emulation [default=true]");
+
 static LIST_HEAD(kernel_fb_helper_list);
 
 /**
@@ -99,6 +104,9 @@ int drm_fb_helper_single_add_all_connectors(struct drm_fb_helper *fb_helper)
        struct drm_connector *connector;
        int i;
 
+       if (!drm_fbdev_emulation)
+               return 0;
+
        mutex_lock(&dev->mode_config.mutex);
        drm_for_each_connector(connector, dev) {
                struct drm_fb_helper_connector *fb_helper_connector;
@@ -129,6 +137,9 @@ int drm_fb_helper_add_one_connector(struct drm_fb_helper *fb_helper, struct drm_
        struct drm_fb_helper_connector **temp;
        struct drm_fb_helper_connector *fb_helper_connector;
 
+       if (!drm_fbdev_emulation)
+               return 0;
+
        WARN_ON(!mutex_is_locked(&fb_helper->dev->mode_config.mutex));
        if (fb_helper->connector_count + 1 > fb_helper->connector_info_alloc_count) {
                temp = krealloc(fb_helper->connector_info, sizeof(struct drm_fb_helper_connector *) * (fb_helper->connector_count + 1), GFP_KERNEL);
@@ -184,6 +195,9 @@ int drm_fb_helper_remove_one_connector(struct drm_fb_helper *fb_helper,
        struct drm_fb_helper_connector *fb_helper_connector;
        int i, j;
 
+       if (!drm_fbdev_emulation)
+               return 0;
+
        WARN_ON(!mutex_is_locked(&fb_helper->dev->mode_config.mutex));
 
        for (i = 0; i < fb_helper->connector_count; i++) {
@@ -320,11 +334,10 @@ int drm_fb_helper_debug_leave(struct fb_info *info)
 }
 EXPORT_SYMBOL(drm_fb_helper_debug_leave);
 
-static bool restore_fbdev_mode(struct drm_fb_helper *fb_helper)
+static int restore_fbdev_mode(struct drm_fb_helper *fb_helper)
 {
        struct drm_device *dev = fb_helper->dev;
        struct drm_plane *plane;
-       bool error = false;
        int i;
 
        drm_warn_on_modeset_not_all_locked(dev);
@@ -348,14 +361,15 @@ static bool restore_fbdev_mode(struct drm_fb_helper *fb_helper)
                if (crtc->funcs->cursor_set) {
                        ret = crtc->funcs->cursor_set(crtc, NULL, 0, 0, 0);
                        if (ret)
-                               error = true;
+                               return ret;
                }
 
                ret = drm_mode_set_config_internal(mode_set);
                if (ret)
-                       error = true;
+                       return ret;
        }
-       return error;
+
+       return 0;
 }
 
 /**
@@ -365,12 +379,18 @@ static bool restore_fbdev_mode(struct drm_fb_helper *fb_helper)
  * This should be called from driver's drm ->lastclose callback
  * when implementing an fbcon on top of kms using this helper. This ensures that
  * the user isn't greeted with a black screen when e.g. X dies.
+ *
+ * RETURNS:
+ * Zero if everything went ok, negative error code otherwise.
  */
-bool drm_fb_helper_restore_fbdev_mode_unlocked(struct drm_fb_helper *fb_helper)
+int drm_fb_helper_restore_fbdev_mode_unlocked(struct drm_fb_helper *fb_helper)
 {
        struct drm_device *dev = fb_helper->dev;
-       bool ret;
-       bool do_delayed = false;
+       bool do_delayed;
+       int ret;
+
+       if (!drm_fbdev_emulation)
+               return -ENODEV;
 
        drm_modeset_lock_all(dev);
        ret = restore_fbdev_mode(fb_helper);
@@ -588,6 +608,9 @@ int drm_fb_helper_init(struct drm_device *dev,
        struct drm_crtc *crtc;
        int i;
 
+       if (!drm_fbdev_emulation)
+               return 0;
+
        if (!max_conn_count)
                return -EINVAL;
 
@@ -710,6 +733,9 @@ EXPORT_SYMBOL(drm_fb_helper_release_fbi);
 
 void drm_fb_helper_fini(struct drm_fb_helper *fb_helper)
 {
+       if (!drm_fbdev_emulation)
+               return;
+
        if (!list_empty(&fb_helper->kernel_fb_list)) {
                list_del(&fb_helper->kernel_fb_list);
                if (list_empty(&kernel_fb_helper_list)) {
@@ -1930,6 +1956,9 @@ int drm_fb_helper_initial_config(struct drm_fb_helper *fb_helper, int bpp_sel)
        struct drm_device *dev = fb_helper->dev;
        int count = 0;
 
+       if (!drm_fbdev_emulation)
+               return 0;
+
        mutex_lock(&dev->mode_config.mutex);
        count = drm_fb_helper_probe_connector_modes(fb_helper,
                                                    dev->mode_config.max_width,
@@ -1973,6 +2002,9 @@ int drm_fb_helper_hotplug_event(struct drm_fb_helper *fb_helper)
        struct drm_device *dev = fb_helper->dev;
        u32 max_width, max_height;
 
+       if (!drm_fbdev_emulation)
+               return 0;
+
        mutex_lock(&fb_helper->dev->mode_config.mutex);
        if (!fb_helper->fb || !drm_fb_helper_is_bound(fb_helper)) {
                fb_helper->delayed_hotplug = true;