WSOD fix.

Lars-Peter Clausen lars at metafoo.de
Wed Dec 29 20:52:39 CET 2010


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Hi

I've just pushed a patch[1] to the 2.6.34 tree which has been proven to be quite
effective, in regarding to fixing the WSOD in my 2.6.37 tree.
Previously turning the screen on and off had a 60% change of resulting in a permanent
WSOD.
Which the patch applied I haven't seen a single WSOD within 100 display on/off cycles.

You'll still see a short WSOD when turning the display on, that is because the fix
add an additional delay of 100ms in the display init sequence and now the backlight
is turned on before the display.

To get a smooth experience the following scripts have been proven to be useful.

#!/bin/sh
# display_on.sh
echo 0 > /sys/class/graphics/fb0/blank
echo 0 > /sys/class/lcd/jbt6k74-lcd/lcd_power
echo 63 > /sys/class/backlight/pcf50633-backlight/brightness

#!/bin/sh
# display_off.sh
echo 0 > /sys/class/backlight/pcf50633-backlight/brightness
echo 4 > /sys/class/lcd/jbt6k74-lcd/lcd_power
echo 4 > /sys/class/graphics/fb0/blank

They make sure that display, backlight and framebuffer are turned on/off in the
correct order.

- - Lars

[1]
http://git.openmoko.org/?p=kernel.git;a=commitdiff;h=43f0161295bc311d09d705db7b381653fbbb9e46
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