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Recently, when the screen blanks after 10 minutes off inactivity. The backlight is turned off and the FN keys can not be used to regulate the light level.
The backlight can manually be switched on again by setting /sys/class/backlight/intel_backlight/bl_power to 1 and everything is back to normal once again. Why is this happening?
Last edited by lordmetroid (2014-04-29 22:40:01)
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For me, it seems like this is what should happen. Why would you want to waste energy/battery on backlight if the screen is blanked anyway?
Besides black pixels actually draw more power on lcds than any other color, so blanking screen without turning the backlight off seems kinda pointless, at least from power consumption point of view.
does the backlight turn off if bl_power is set to 1, and screen blanks?
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Yes, of course one want the backlight to turn off when the screen goes blank.
However, I would prefer if the backlight turned on again when the laptop is active once again.
Last edited by lordmetroid (2014-04-29 22:40:20)
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It seems that if the backlight is turned off again after I written 1 to bl_power, I then have to write 0 instead of 1 to turn it on.
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sorry, I misunderstood the issue from your first post. Don't really have ideas what could be causing this though.
You could try if this happens with older kernel, as it is one of the most likely culprits.
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This bug happen rescently so it is probably something that happen in the new kernel.
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