sunxi: video: Add support for LCD reset pin

On some boards there is a gpio to reset the LCD panel, add support for this.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Ian Campbell <ijc@hellion.org.uk>

board/sunxi/Kconfig

@@ -312,6 +312,14 @@ config VIDEO_LCD_POWER
 	Set the power enable pin for the LCD panel. 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_RESET
+	string "LCD panel reset pin"
+	depends on VIDEO
+	default ""
+	---help---
+	Set the reset pin for the LCD panel. 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_BL_EN
 	string "LCD panel backlight enable pin"
 	depends on VIDEO

drivers/video/sunxi_display.c

@@ -592,7 +592,7 @@ static void sunxi_lcdc_enable(void)
 
 static void sunxi_lcdc_panel_enable(void)
 {
-	int pin;
+	int pin, reset_pin;
 
 	/*
 	 * Start with backlight disabled to avoid the screen flashing to
@@ -610,6 +610,12 @@ static void sunxi_lcdc_panel_enable(void)
 		gpio_direction_output(pin, PWM_OFF);
 	}
 
+	reset_pin = sunxi_name_to_gpio(CONFIG_VIDEO_LCD_RESET);
+	if (reset_pin != -1) {
+		gpio_request(reset_pin, "lcd_reset");
+		gpio_direction_output(reset_pin, 0); /* Assert reset */
+	}
+
 	/* Give the backlight some time to turn off and power up the panel. */
 	mdelay(40);
 	pin = sunxi_name_to_gpio(CONFIG_VIDEO_LCD_POWER);
@@ -617,6 +623,9 @@ static void sunxi_lcdc_panel_enable(void)
 		gpio_request(pin, "lcd_power");
 		gpio_direction_output(pin, 1);
 	}
+
+	if (reset_pin != -1)
+		gpio_direction_output(reset_pin, 1); /* De-assert reset */
 }
 
 static void sunxi_lcdc_backlight_enable(void)