mt6762添加gpio按键方法与问题调试

mt6762添加gpio按键方法与问题调试
1 配置dts文件．定义gpio87为拍照键,对于keycode = 212.
gpio_keys:gpio_keys {
        compatible = "gpio-keys";
        input-name = "gpio-keys";
        autorepeat;

        key_camera {
            label = "Camera Key";
            linux,code = <212>;
            gpios = <&pio 87 0x01>;
            gpio-key,wakeup;
        };
    }

２设备驱动在kernel-4.9/drivers/input/keyboard/gpio_keys.c中初始化．

如果该gpio在别的设备被定义为其它其它GPIO口或中断口，会导致初始化报错，如在其它设备被定义为中断口，则打印kmsg　log会出现下面初始化错误提示：

<3>[    2.507707] .(2)[1:swapper/0]gpio-keys gpio_keys: Unable to claim irq 105; error -16
<4>[    2.508721] .(2)[1:swapper/0]gpio-keys: probe of gpio_keys failed with error -16

初始化成功后，应该为：
[    2.625807] .(1)[1:swapper/0]input: gpio_keys as /devices/platform/gpio_keys/input/input2

3 可以在framework抓取底层上报的按键信息．
在文件
alps/frameworks/base/services/core/java/com/android/server/policy/PhoneWindowManager.java
设置DEBUG_INPUT = true;打印按键信息．
在下面方法里可以添加打印log.
    /** {@inheritDoc} */
    @Override
    public long interceptKeyBeforeDispatching(WindowState win, KeyEvent event, int policyFlags) {

．．．

．．．

}