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I could disable ATI discrete graphics in Ubuntu 13.10 with this command:

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

But in Ubuntu 14.04 it does not work. cat /sys/kernel/debug/vgaswitcheroo/switch shows the same:

0:IGD:+:DynPwr:0000:01:05.0 
1:DIS-Audio: :Pwr:0000:02:00.1 
2:DIS: :DynPwr:0000:02:00.0 

What should I do in Ubuntu 14.04?

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i do all of that.but the answer of cat /sys/kernel/debug/vgaswitcheroo/switch is same : 0:IGD:+:DynPwr:0000:01:05.0 1:DIS-Audio: :Pwr:0000:02:00.1 2:DIS: :DynPwr:0000:02:00.0 in ubuntu 14.04 some thing is different ?? –  user278445 May 6 at 4:20
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1 Answer 1

In this version of Ubuntu, Dynamic Radeon Drivers are included and activated so that the old solution that you mention does not work.

To operate the old solution you can edit the file /etc/default/grub.

In this file you can add the option radeon.runpm=0 in the call to the current kernel (usually after ro quiet splash).

Alternatively, you can also add radeon.runpm=0 to the value of the variable GRUB_CMDLINE_LINUX_DEFAULT, then save and run sudo update-grub.

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attempted this solution with a Hp dv7-4263cl / radeon HD4225 / HD6370 and had no change in the results of the content of the switcheroo file. –  Charles Green May 28 at 15:43
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@CharlesGreen You could try turn_off_gpu.sh from acpi_call. See Arch wiki : Fully Power Down Discrete GPU for instructions. –  bain May 28 at 19:58
    
Thanks! I may give that a try: I'm going to give the AMD drivers a shot, assuming they go from beta to release fairly soon. If that does not do the trick, I'll head to this solution. –  Charles Green May 28 at 20:32
    
Sigh - the beta drivers from AMD did not work for me - something in the HP prevents them from recognizing the hardware... –  Charles Green May 29 at 0:33
    
@CharlesGreen (or anyone else with this issue) - if you are using the open source drivers, and have problems with radeon power management and specific hardware, then asking about it on the radeon driver mailing list at lists.x.org/mailman/listinfo/xorg-driver-ati is more likely to get an accurate response. With the latest drivers, radeon power management should really "just work"; if it does not work for some cards then the developers need to know what is broken so they can fix it. –  bain 2 days ago
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