Rather than signaling a full update of the display from userspace via a console switch, this patch introduces 2 files int /sys/power, wait_for_fb_sleep and wait_for_fb_wake. Reading these files will block until the requested state has been entered. When a read from wait_for_fb_sleep returns userspace should stop drawing. When wait_for_fb_wake returns, it should do a full update. If either are called when the fb driver is already in the requested state, they will return immediately. Signed-off-by: Rebecca Schultz <rschultz@google.com> Signed-off-by: Arve Hjønnevåg <arve@android.com> (cherry picked from commit 4b0ea27fc8202b21ce338c82b55eee9c281bd7da)