apalis-imx8: turn off lcd backlight before os handover

U-Boot typically tears down the display controller before handing
control over to Linux. On LCD displays disabling pixel clock leads to a
fading out effect with vertical/horizontal lines. Make sure to disable
back light GPIO Apalis BKL1 before booting Linux.

Signed-off-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>
Signed-off-by: Francesco Dolcini <francesco.dolcini@toradex.com>
Reviewed-by: Fabio Estevam <festevam@denx.de>

diff --git a/board/toradex/apalis-imx8/apalis-imx8.c b/board/toradex/apalis-imx8/apalis-imx8.c
index 6f28367..1622900 100644 (file)
--- a/board/toradex/apalis-imx8/apalis-imx8.c
+++ b/board/toradex/apalis-imx8/apalis-imx8.c
@@ -182,9 +182,18 @@ int board_early_init_f(void)
 }
 
 #if CONFIG_IS_ENABLED(DM_GPIO)
+
+#define BKL1_GPIO   IMX_GPIO_NR(1, 10)
+
+static iomux_cfg_t board_gpios[] = {
+       SC_P_LVDS1_GPIO00 | MUX_MODE_ALT(3) | MUX_PAD_CTRL(GPIO_PAD_CTRL),
+};
+
 static void board_gpio_init(void)
 {
-       /* TODO */
+       imx8_iomux_setup_multiple_pads(board_gpios, ARRAY_SIZE(board_gpios));
+
+       gpio_request(BKL1_GPIO, "BKL1_GPIO");
 }
 #else
 static inline void board_gpio_init(void) {}
@@ -202,6 +211,14 @@ int board_phy_config(struct phy_device *phydev)
 }
 #endif
 
+/*
+ * Backlight off before OS handover
+ */
+void board_preboot_os(void)
+{
+       gpio_direction_output(BKL1_GPIO, 0);
+}
+
 int checkboard(void)
 {
        puts("Model: Toradex Apalis iMX8\n");