sunxi: video: Add support for external DAC enable pin

The external DAC for VGA output might have either a power or reset
control pin that needs to be pulled up, as is the case on the
Hummingbird A31.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Acked-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
diff --git a/board/sunxi/Kconfig b/board/sunxi/Kconfig
index 5822b41..c5105bb 100644
--- a/board/sunxi/Kconfig
+++ b/board/sunxi/Kconfig
@@ -314,6 +314,14 @@
 	LCD interface driving a VGA connector, such as found on the
 	Olimex A13 boards.
 
+config VIDEO_VGA_EXTERNAL_DAC_EN
+	string "LCD panel power enable pin"
+	depends on VIDEO_VGA_VIA_LCD
+	default ""
+	---help---
+	Set the enable pin for the external VGA DAC. This takes a string in the
+	format understood by sunxi_name_to_gpio, e.g. PH1 for pin 1 of port H.
+
 config VIDEO_LCD_MODE
 	string "LCD panel timing details"
 	depends on VIDEO