引脚定义为GPIO的过程：

需要修改imx6ul-pinfunc.h，imx6ul-14x14-evk.dts两个文件，目录是arch/arm/boot/dts/，如下：

1、确保要是用的引脚有gpio的定义

2、将该引脚在iomux处其他的定义注释掉

将其定义为如下：

pinctrl-names = "default";

         pinctrl-0 = <&pinctrl_hog_1>;

         imx6ul-evk {

                   pinctrl_hog_1: hoggrp-1 {

                            fsl,pins = <

                                     MX6UL_PAD_LCD_RESET__WDOG1_WDOG_ANY    0x30b0

                                     MX6UL_PAD_UART1_RTS_B__GPIO1_IO19   0x17059 /* SD1 CD */

                                     MX6UL_PAD_GPIO1_IO05__USDHC1_VSELECT     0x17059 /* SD1 VSELECT */

                                     MX6UL_PAD_GPIO1_IO09__GPIO1_IO09        0x17059 /* SD1 RESET */

                                     MX6UL_PAD_SNVS_TAMPER0__GPIO5_IO00         0x80000000 /* ACC INT */

                                     MX6UL_PAD_CSI_DATA00__GPIO4_IO21       0x3008

                                     MX6UL_PAD_CSI_DATA01__GPIO4_IO22       0x3008

                                     MX6UL_PAD_CSI_DATA02__GPIO4_IO23       0x3008

                                     MX6UL_PAD_CSI_DATA03__GPIO4_IO24       0x3008

                                     MX6UL_PAD_CSI_DATA04__GPIO4_IO25       0x3008

                   >;

};