记开启HDCP功能后无法恢复出厂设置

最近在RK3288 Android4.4.2平台上开启了HDCP功能后，如果不烧录Key，在恢复出厂设置（实质就是执行reboot recovery命令）时会出现卡死，无法重启，即未关机就卡死了，后来发现是Kernel里的CONFIG_FW_LOADER_USER_HELPER配置项导致。

工具/原料

RK3288板卡

Android4.4.2系统

方法/步骤

最近在RK3288 Android4.4.2平台上开启了HDCP功能后，如果不烧录Key，在恢复出厂设置（实质就是执行reboot recovery命令）时会出现卡死，无法重启，即未关机就卡死了。

后来发现是Kernel里的CONFIG_FW_LOADER_USER_HELPER配置项导致，将该选项默认关闭就可以解决该问题。

但会影响到system/displayd/Hdcp.cpp这个文件里的操作，目前测试不影响，也不清楚该服务有何作用。暂时先这样处理了。

卡死时的串口信息如下：

[  288.874429] SysRq : Emergency Remount R/O

[  288.880282] EXT4-fs (mmcblk0p8): re-mounted. Opts: (null)

[  288.880790] EXT4-fs (mmcblk0p11): re-mounted. Opts: (null)

[  288.904231] EXT4-fs (mmcblk0p12): re-mounted. Opts: (null)

[  288.911990] Emergency Remount complete

[  288.978715] cpufreq: reboot set core rate=1200000000, volt=1112500

[  289.477580] EXT4-fs (mmcblk0p12): ext4_da_writepages: jbd2_start: 8192 pages, ino 489; err -30

[  289.486096] EXT4-fs (mmcblk0p12): ext4_da_writepages: jbd2_start: 8192 pages, ino 489; err -30

[  291.456866] EXT4-fs (mmcblk0p12): ext4_da_writepages: jbd2_start: 2048 pages, ino 489; err -30

……

[  370.412868] SysRq : Show Blocked State

[  370.416566]   task                PC stack   pid father

[  370.421698] init            D c0784b5c     0     1      0 0x00000000

[  370.427978] [] (__schedule+0x48c/0x554) from [] (__down_write_nested+0x78/0xc0)

[  370.436871] [] (__down_write_nested+0x78/0xc0) from [] (__usermodehelper_disable+0x24/0x104)

[  370.446872] [] (__usermodehelper_disable+0x24/0x104) from [] (kernel_restart_prepare+0x28/0x38)

[  370.457128] [] (kernel_restart_prepare+0x28/0x38) from [] (kernel_restart+0xc/0x50)

[  370.466359] [] (kernel_restart+0xc/0x50) from [] (SyS_reboot+0x150/0x1b0)

[  370.474740] [] (SyS_reboot+0x150/0x1b0) from [] (ret_fast_syscall+0x0/0x30)

[  370.483293] kworker/0:1     D c0784b5c     0    30      2 0x00000000

[  370.489560] Workqueue: events request_firmware_work_func

好的，就CONFIG_FW_LOADER_USER_HELPER这配置影响到了，关了吧。