[PATCH v3 02/20] apalis-imx8: turn off lcd backlight before os handover

Francesco Dolcini
2023-01-16T19:06:31Z

From: Marcel Ziswiler <marcel.ziswiler@toradex.com>

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>
---
v3: added Reviewed-by: Fabio
v2: no changes
---
board/toradex/apalis-imx8/apalis-imx8.c | 19 ++++++++++++++++++-
1 file changed, 18 insertions(+), 1 deletion(-)

diff --git a/board/toradex/apalis-imx8/apalis-imx8.c b/board/toradex/apalis-imx8/apalis-imx8.c
index 6f28367cf034..1622900bd1da 100644
--- 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");
--
2.25.1