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Tuesday, 2 February 2010

David Airlie solves Intel/ATI and ATI/ATI switchable graphics, mjg59 solves nvidia in nouveau land

Not much more to say apart from "We've got it!".

We started this blog a year ago and we were hopeful that switchable graphics in Linux would be a reality some day. David Airlie's patch for the Intel/ATI and ATI/ATI configurations, together with mjg59's work on nvidia support in nouveau completes the basic kernel/hardware support in Linux.

As David Airlie's post suggests at the end, there is still work to be done in the gdm/Xorg side of things, but current support is comparable to Apple's OSX switchable graphics capabilities. Windows 7 is still one step ahead with seamless hot switching in new laptop models...

airlied: hybrid graphics on Linux (Part 2)
Okay v4 of the patch is available at

http://people.freedesktop.org/~airlied/vgaswitcheroo/
http://people.freedesktop.org/~airlied/vgaswitcheroo/0001-vga_switcheroo-initial-implementation-v4.patch

First thing I added was power up/down methods. This calls the DRM suspend/resume methods + along with the cut power for discrete GPU. I'm not sure dynamic Windows ever does this as it seems to take a bit of work, I suspect they just run the second GPU in really low power modes. This is slow because we have to repost the ATI card after turning it back on.

I then talked to mjg59 and worked over the ATPX detection. I removed all the DMI code and it should detect *any* laptop that uses ATPX (i.e. ATI/ATI and Intel/ATI) from what I can see. I've tested on Lenovo W500 and T500 now and it appears to work on both. Would be nice if someone on a ATI/ATI and/or ASUS ATI/ATI or ATI/Intel machines could give it a whirl. I think the main problem with ATI/ATI is the poweroff methods have a hardcoded Intel PCI ID. I've no idea yet how to tell on an ATI/ATI which device is the IGD and which is discrete. Its probably more than likely the IGD is the one with the ATPX method on it.

It doesn't switch off at boot yet but I've added commands to let you do it.

echo "OFF" > switch - turns off the not in use card, so if Intel and ATI are on at boot, it will turn off ATI
echo "ON" > switch - turns back on not in use card
echo "PCIID" > switch - causes a switch with full off/on cycles.

nvidia combos appear to use a DSM method and in theory nouveau_acpi.c should be detecting that, so it might be possible for someone to hook that up.

I've also started looking at some desktop integration via gdm or logout - but its not my usual place to code so going is a bit slower ;-)


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