PM: earlysuspend: Hack Compatability shim layer for earlysuspend sysfs files.

Since early suspend was dropped in 3.3 kernels, old (4.1 and lower)
versions of Android userland poll looking for
/sys/power/wait_for_fb_sleep and /sys/power/wait_for_fb_wake.

This burns cpu time, affecting performance and adds noise to the
log.

So I've found the driver that adds theses files and hacked out
its dependency on the earlysuspend infrastructure, so calls
to /sys/power/wait_for_fb_sleep block and /sys/power/wait_for_fb_wake
always return awake.

The compatability shim originated with the following commit:

commit 6753172b8a439cf9ac466e7dc31780a39f255ec2
Author: Rebecca Schultz <rschultz@google.com>
Date:   Thu Jul 17 18:14:55 2008 -0700

    PM: earlysuspend: Removing dependence on console.

    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>

[jstultz: Reworked as an interface shim so userland is happpy]
Signed-off-by: John Stultz <john.stultz@linaro.org>

0 files changed, 0 insertions, 0 deletions