/**********************************************************************

 *                I.MX6 KEY_ROW4 can't as GPIO pin

 * 说明：

 *     Tony遇到KEY_ROW4作为GPIO口时无法设置高、低电平问题，后来通过在

 * 相关patch中找到方法，很特殊。

 *

 *                                  2016-11-26 深圳 南山平山村 曾剑锋

 *********************************************************************/

一、参考文档：

    . android-imx6-kitkat/kernel_imx.git/3.0./SR--Split-C1-to-C1-and-microsom.patch

        https://github.com/rabeeh/android-imx6-kitkat/blob/master/kernel_imx.git/3.0.35/SR-0013-Split-C1-to-C1-and-microsom.patch

    . [meta-freescale] [PATCH] Added support for the SolidRun HummingBird    (also known as Carrier One)

        https://lists.yoctoproject.org/pipermail/meta-freescale/2014-January/006271.html

二、解决方法：

    #define MX6DL_ENET_PAD_CTRL_PD (PAD_CTL_PKE | PAD_CTL_PUE  |        \

            PAD_CTL_PUS_100K_DOWN | PAD_CTL_SPEED_MED |        \

            PAD_CTL_DSE_40ohm   | PAD_CTL_HYS)

    IOMUX_PAD(0x0650, 0x0268, , 0x0000, , MX6DL_ENET_PAD_CTRL_PD), /* KEY_ROW4 reset signal */