Synchronization is needed,to make sure, read() is not called
by hwcVsyncThread when VSYNC is disabled.
Otherwise in usecases, where display is OFF, and still some
tasks keep running in the background; SurfaceFlinger hogs
CPU.
(cherry picked from commit ffa84468bbd2517ffb22ab4023cb57a6272fc80d)
Change-Id: Idd779647a27ed3e6fb0703a07033dd5f7cd1b5fd
* Read sysfs entries, to get vsync timestamp from kernel.
* External display continues to use in ueventThread.
* A new thread, vsyncThread is created to read and send vsync
timestamps to HAL.
* Disable H/W VSYNC for MDP 5.x targets until kernel changes are
complete.
(cherry picked from commit a61a58cb775631cd3899211f6ff0aed232f5f3c0)
Change-Id: I58e09a092f81d4ff78b8cb4072ff06d2500c6f53
