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I know 14.04 has Kernel 3.13 and is supposed to be better at dynamic power management. My problem is the estimated remaining time keeps changing. But on an average I see 5 hours.

On same machine on Linux mint 15 (based off 13.04) I used vgaswitcharoo method and used to get at least 6 hours.

echo OFF > /sys/kernel/debug/vgaswitcheroo/switch

Does not work any more.

I've tried acpi_call method mentioned here : http://www.noobslab.com/2013/10/enable-laptop-mode-and-other-tweaks-to.html Unfortunately my card isn't listed/supported

Also (unsuccessfully) tried : http://www.webupd8.org/2014/04/prevent-your-laptop-from-overheating.html

In case there are card specific suggestions, I have following cards:

$ lspci -nn | grep VGA                               
00:02.0 VGA compatible controller [0300]: Intel Corporation 3rd Gen Core processor Graphics Controller [8086:0166] (rev 09)
01:00.0 VGA compatible controller [0300]: Advanced Micro Devices, Inc. [AMD/ATI] Thames [Radeon HD 7500M/7600M Series] [1002:6840] (rev ff)
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2 Answers 2

This seems to be a bug.

Have you checked the output of # cat /sys/kernel/debug/vgaswitcheroo/switch?

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Here is the output 0:IGD:+:Pwr:0000:00:02.0 1:DIS: :DynOff:0000:01:00.0 –  Mandar Vaze May 26 at 10:39
    
I've already marked the said bug as "It Affects me too" on launchpad long time ago. –  Mandar Vaze May 26 at 10:59
    
If you don't want to use the ATI card you can disable it permanently by blacklisting the radeon mod. This will definitely improve your battery life! –  rawcoder May 27 at 6:51
    
from ubuntuforums.org/… "adding blacklist radeon to blacklist.conf doesn't seem to work. It does nothing, essentially" –  Mandar Vaze May 30 at 17:17

I used powertop. I have Ubuntu 14.04 installed on a Dell Inspiron 15R 5523 laptop with AMD/Intel Hybrid graphics. I AM NOT SURE if this will work for you, but I don't think it will break the system(because powertop is pretty reliable) so nothing wrong in trying. In powertop(check out its website for downloads and usage procedures), after changing all the 'bad' parameters to 'good' in the "Tunables" tab, suddenly my fan speed decreased and so did the laptop temperature.

I have not installed any drivers(and the Catalyst Control Center) for the discrete ATI Raedon card, just the Intel Open Source drivers form the Intel website.

Since settings are not preserved on reboot, after bit experimentation, I found that changing 'bad' parameters to 'good' of the "Runtime PM for PCI Device Advanced Micro Devices, Inc. [AMD/ATI] Mars [Radeon HD 8730M]" and of each of "Enable SATA link power Management for host0" Enable SATA link power Management for host1" Enable SATA link power Management for host2" Enable SATA link power Management for host3" Enable SATA link power Management for host4" and "Enable SATA link power Management for host5". I tried to copy their echo commands onto the /etc/rc.local file to auto-execute them each time the system booted up, but it did not work (automatically 'bad' for the "...host0/1/2/3/4/5" in the Tunables tab of powertop).

I even went to the extent of checking if it really was reverted to the 'auto'(default) value in the source file...and I found, yes, it was. So, basically, this might work for a few people. Give it a try. If anyone figures out(with testing) how to keep it permanent(i.e. persistent after reboot). Currently I am not rebooting my laptop, just closing my lid to prevent doing this every damn time I reboot.

Give it a try and do comment/like if it works for you. Just want to know if this is a viable solution for a general installation in any laptop with Intel/AMD Hybrid graphics.

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