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Power saving features with OSS ati driver

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  • Power saving features with OSS ati driver

    Hi all guys and gals, this is my first post in the forum, but I visit phoronix very often for good and nice news about the Linux world.

    I want to ask something about the current status of power saving features currently implemented inside ati and radeonhd OSS drivers.
    I have a laptop with HD3450 and currently I'm using fglrx driver with powerplay always enabled to raise battery lifetime and reduce heat production. I Switched to ati OSS driver built in X but I get a bit worse temperatures, even when I use DynamicClocks option in X11. Ati OSS driver IMHO has better 2D performances than fglrx, but I absolutely don't need the graphic card to run at maximum.

    Is there a way to check (and maybe set?) engine and memory clocks of the graphic card with ati or radeonhd drivers?

    Currently I'm using Fedora 11 x64 with kernel 2.6.30 and no unstable drivers at all, but everything is updated using rpmfusion and official repos.

    Thank you!

  • #2
    There is a "ForceLowPowerMode" option, but you might need to upgrade your driver.

    you'll get some more saving that way (at the price of performance), but not as well as with fglrx.


    • #3
      Why not as much as fglrx?
      I mean, isn't enough to downclock/downvolt GPU and memory?
      I'm absolutely not worried about performances, since there's still no 3D working component for R600.


      • #4
        When you're using Fedora 11 you're also using kms, which means that the modesetting is done in the kernel (which e.g. makes vt-switching very fast and suspend/resume more reliable). Unfortunately radeons powersaving-options and kms don't work together yet.
        I'm not sure, but maybe they'll work when you add nomodeset to your kernel boot parameters in grub.


        • #5
          Why not as much as fglrx?
          Because fglrx does aggressive, load-based, dynamic power-saving, and the open-source drivers basically just downclock and reduce voltage by half. If you're not using KMS.

          OSS driver powersaving is quite basic at the moment. Proper powersaving will come in the kernel once the whole KMS stuff stabilises.

          since there's still no 3D working component for R600
          There is (and it's very good), but you have to build from git.


          • #6
            I've tried 'radeon.dynclks=1' kernel parm also with KMS and it does not appear to have an effect at this point. Kernel power management + KMS will be a great milestone. One thing at a time I suppose.


            • #7
              I understand. So I think I have to wait newer kernel and newer OSS drivers to fully appreciate OSS powersaving features, right?


              • #8

                Once 3D over KMS is stable (which should be relatively soon, I guess), powersaving should be the next priority.

                It still might take a while before it's comparable to fglrx.