board: imx6ull: Add disable PMIC_STBY_REQ

Disable output driver of PAD CCM_PMIC_STBY_REQ. This prevents the
SOC to request for a lower voltage during sleep. This is necessary
because the voltage is changing too slow for the SOC to wake up
properly.

Signed-off-by: Philippe Schenker <philippe.schenker@toradex.com>
Acked-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>
Reviewed-by: Igor Opaniuk <igor.opaniuk@toradex.com>
diff --git a/board/toradex/colibri-imx6ull/colibri-imx6ull.c b/board/toradex/colibri-imx6ull/colibri-imx6ull.c
index b6f45ed..f1d5cc6 100644
--- a/board/toradex/colibri-imx6ull/colibri-imx6ull.c
+++ b/board/toradex/colibri-imx6ull/colibri-imx6ull.c
@@ -50,6 +50,8 @@
 #define LCD_PAD_CTRL    (PAD_CTL_HYS | PAD_CTL_PUS_100K_UP | \
 		PAD_CTL_DSE_48ohm)
 
+#define MX6_PAD_SNVS_PMIC_STBY_REQ_ADDR 0x2290040
+
 #define NAND_PAD_CTRL (PAD_CTL_DSE_48ohm | PAD_CTL_SRE_SLOW | PAD_CTL_HYS)
 
 #define NAND_PAD_READY0_CTRL (PAD_CTL_DSE_48ohm | PAD_CTL_PUS_22K_UP)
@@ -331,6 +333,14 @@
 		env_set("variant", "-wifi");
 #endif
 
+	/*
+	 * Disable output driver of PAD CCM_PMIC_STBY_REQ. This prevents the
+	 * SOC to request for a lower voltage during sleep. This is necessary
+	 * because the voltage is changing too slow for the SOC to wake up
+	 * properly.
+	 */
+	__raw_writel(0x8080, MX6_PAD_SNVS_PMIC_STBY_REQ_ADDR);
+
 #ifdef CONFIG_CMD_BMODE
 	add_board_boot_modes(board_boot_modes);
 #endif