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Thread: Does the AMD open source driver support muxless switchable hybrid laptops?

  1. #1
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    Default Does the AMD open source driver support muxless switchable hybrid laptops?

    Hi to all.
    I would like to buy a toshiba P50-B-11M laptop with the Radeon R9 M265X GPU, and I would like to use only open source drivers.
    Does the opne source AMD driver support muxless switchable devices like that out of the box?
    In case does it automatically activate the discrete GPU in case of huge graphical loads are requested?
    And what about gaming with wine (my games are Gran Prix Legends, IL2 sturmvich) and not (Xplane9)?
    Thank you,
    Xwang

  2. #2
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    Quote Originally Posted by Xwaang View Post
    Hi to all.
    Does the opne source AMD driver support muxless switchable devices like that out of the box?
    In case does it automatically activate the discrete GPU in case of huge graphical loads are requested?
    It does or at least tries, on my laptop with a R9 M290X the discrete card gets powered off at system startup but then resuming it for games fails (I don't have the dmesg lines but it says that the ring test fails so acceleration is disabled).

    The workaround is to simply leave the discrete card powered with the kernel argument radeon.runpm=0. At low voltage and unused my M290X stays at around 40C. Then you can switch to the discrete card with DRI_PRIME=1 ./Game

    Quote Originally Posted by Xwaang View Post
    And what about gaming with wine (my games are Gran Prix Legends, IL2 sturmvich) and not (Xplane9)?
    That would be the radeonsi current state, it's not specific to muxless laptops afaik.

    I haven't tested extensively games yet so can't say.

  3. #3
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    There is:
    * dpm "dynamic power management": Automatically sets the clock speed (and probably a few others things) according to the workload.
    * runpm "runtime power management": Powers off a gpu when nothing is being rendered on it.
    * PRIME offloading:
    Someone correct me if I'm wrong.
    I think xf86-video-ati still doesn't have dri3 support upstream, so after starting X you'll have to run "xrandr --listproviders" and hopefully see both gpus there and then run "xrandr --setprovideroffloadsink 2 1" (2 being the id of the second gpu and 1 being the id of the first gpu, which listproviders shows). Then the environment variable DRI_PRIME=1 can be set and every opengl program with that environment will render on the second GPU.
    With this fork https://github.com/iXit/xf86-video-ati there is dri3 support and the whole fiddling with xrandr isn't necessary anymore.


    There is NOT:
    * Completely dynamic offloading like in windows. You can't move a running program from one gpu to another one.
    * Automatic offloading. Programs only render on another GPU if you tell them to.
    * Crossfire. Using the ressources of multiple GPUs is not supported yet. But from what we hear, even in the proprietary driver it doesn't work well anyway.

  4. #4
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    Quote Originally Posted by haagch View Post
    I think xf86-video-ati still doesn't have dri3 support upstream, so after starting X you'll have to run "xrandr --listproviders" and hopefully see both gpus there and then run "xrandr --setprovideroffloadsink 2 1" (2 being the id of the second gpu and 1 being the id of the first gpu, which listproviders shows).
    I don't need to do that to get DRI_PRIME working, from my limited understanding this is what DRI_PRIME enforces.

  5. #5
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    Quote Originally Posted by haagch View Post
    * Automatic offloading. Programs only render on another GPU if you tell them to.
    Also wrong, it's automatic (I saw the GPU LED changing color when running games with runpm on) although I can't check if it's smart enough to do it for every game since runpm isn't usable yet on my laptop.

  6. #6
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    Quote Originally Posted by Azultra View Post
    Also wrong, it's automatic (I saw the GPU LED changing color when running games with runpm on) although I can't check if it's smart enough to do it for every game since runpm isn't usable yet on my laptop.
    Well, that would be news to me. Is there any documentation about this?

    I'm using intel gpu + radeon gpu and in the beginning there were a few bugs left where the radeon gpu was mistakenly powered on when certain x functionality was used.
    Just saying it could be something like that.

  7. #7
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    And what about hdmi and so on?
    Should I turn on the discrete card to use it on the laptop?

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