U-boot pin configure

I am working in a with a colibri-imx7d. I need to change the default pin configuration.
The imx7d pin that I have to change has a 100 kohm pull down resistor and I need to change it for a 5 kohm pull up resistor, I made this change in the board_init u-boot function.
To make my changes I took other pin configuration in u-boot as example, my changes are:

 board/toradex/colibri_imx7/colibri_imx7.c | 40 +++++++++++++++++++++++
 1 file changed, 40 insertions(+)
diff --git a/board/toradex/colibri_imx7/colibri_imx7.c b/board/toradex/colibri_imx7/colibri_imx7.c
index a4a3484a891..6d7a332ad96 100644
--- a/board/toradex/colibri_imx7/colibri_imx7.c
+++ b/board/toradex/colibri_imx7/colibri_imx7.c
@@ -52,9 +52,15 @@ DECLARE_GLOBAL_DATA_PTR;
+#define FGS_POWER_DOWN  IMX_GPIO_NR(1, 7)

+static iomux_v3_cfg_t const power_down_pads[] = {

 int board_init(void)
+	// Power down pin is configures as 5 kohm pull up resistor for hardware requiremnt. Check CYL-108
+	imx_iomux_v3_setup_multiple_pads(power_down_pads, ARRAY_SIZE(power_down_pads));
+	gpio_request(FGS_POWER_DOWN, "power-down");
+	gpio_free(FGS_POWER_DOWN);

This configuration is working but I dont know if it is the correct way to do it, if someone has documantation or can explain how is the best way to change pin configuration in u-boot please tell me.

How I said, the change of pin configuration is working but we measure pin status with oscilloscope and we note that the change takes about 300 miliseconds to take effect, is this delay time to take effect normal? I mean, is a kind of hardware limitation this time? I already know that I can solder a pull up resistor but I want t know if is possible to make this change earlier.

To do a selected pin configuration slightly faster you can do it in the board_early_init_f() function. Please be aware about limitation. Check this document for details.
External pull-up is definitely recommended if you need a shortest possible time .