how to enable "wait for vertical sync" on i915 framebuffer driver?

[pengxihan at gmail.com (hank peng)]

Hi:
I need to enable this function in use space programe, but I found that
it is not implemented in i915 fb driver. I used FBIO_WAITFORVSYNC
ioctl command, then what should I do?

-- 
The simplest is not all best but the best is surely the simplest!