@@ -35,7 +35,8 @@
#include <linux/export.h>
#include <drm/drmP.h>
#include <drm/drm_crtc.h>
-#include <linux/videomode.h>
+#include <linux/of.h>
+#include <linux/of_videomode.h>
/**
* drm_mode_debug_printmodeline - debug print a mode
@@ -541,6 +542,38 @@ int drm_display_mode_from_videomode(const struct videomode *vm,
EXPORT_SYMBOL_GPL(drm_display_mode_from_videomode);
#endif
+#if IS_ENABLED(CONFIG_OF_VIDEOMODE)
+/**
+ * of_get_drm_display_mode - get a drm_display_mode from devicetree
+ * @np: device_node with the timing specification
+ * @dmode: will be set to the return value
+ * @index: index into the list of display timings in devicetree
+ *
+ * This function is expensive and should only be used, if only one mode is to be
+ * read from DT. To get multiple modes start with of_get_display_timings and
+ * work with that instead.
+ */
+int of_get_drm_display_mode(const struct device_node *np,
+ struct drm_display_mode *dmode, unsigned int index)
+{
+ struct videomode vm;
+ int ret;
+
+ ret = of_get_videomode(np, &vm, index);
+ if (ret)
+ return ret;
+
+ drm_display_mode_from_videomode(&vm, dmode);
+
+ pr_info("%s: got %dx%d display mode from %s\n", __func__, vm.hactive,
+ vm.vactive, np->name);
+ drm_mode_debug_printmodeline(dmode);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(of_get_drm_display_mode);
+#endif
+
/**
* drm_mode_set_name - set the name on a mode
* @mode: name will be set in this mode
@@ -56,6 +56,7 @@
#include <linux/cdev.h>
#include <linux/mutex.h>
#include <linux/slab.h>
+#include <linux/of.h>
#include <linux/videomode.h>
#if defined(__alpha__) || defined(__powerpc__)
#include <asm/pgtable.h> /* For pte_wrprotect */
@@ -1459,6 +1460,11 @@ drm_mode_create_from_cmdline_mode(struct drm_device *dev,
extern int drm_display_mode_from_videomode(const struct videomode *vm,
struct drm_display_mode *dmode);
#endif
+#if IS_ENABLED(CONFIG_OF_VIDEOMODE)
+extern int of_get_drm_display_mode(const struct device_node *np,
+ struct drm_display_mode *dmode,
+ unsigned int index);
+#endif
/* Modesetting support */
extern void drm_vblank_pre_modeset(struct drm_device *dev, int crtc);