On Sat, Mar 5, 2016 at 9:16 AM, Lukas Wunner <lukas@xxxxxxxxx> wrote: > Hi Bastien, > > On Fri, Mar 04, 2016 at 04:12:27PM +0000, Bastien Nocera wrote: >> Lukas Wunner <lukas <at> wunner.de> writes: >> > Enable GPU switching on the pre-retina MacBook Pro (2008 - 2013), v5. >> >> I've tested your patchset on a MacBookPro8,1, with an integrated Intel and >> discrete AMD/ATI GPUs. > > Hm, it must be either an 8,2 or 8,3. The 8,1 was a 13" machine and only > had an integrated GPU. > > >> I've used the COPR repository here to cut down on my compilation time: >> https://copr.fedorainfracloud.org/coprs/firstyear/kernel-mbp/ >> >> I'm not certain how to test out your changes, or what the consequences should >> be on a stock Fedora 23/GNOME 3.18 installation. After booting (note that I >> did not change any command-line options in grub), a gnome-shell/gdm X11 >> session comes up (I disabled Wayland, to rule out behavioural changes), I'd >> log in to GNOME and gnome-shell (which starts another X11 session on >> another VT). > > Switching and power control currently requires manual intervention > by echoing commands to /sys/kernel/debug/vgaswitcheroo/switch > as documented here: > https://01.org/linuxgraphics/gfx-docs/drm/modes_of_use.html > > As you've correctly observed, the machine is initially switched to > the discrete GPU and both GPUs are turned on. By echoing "IGD" to > the sysfs file, you'll switch to the integrated GPU and turn off > the discrete GPU. > > It's possible to let the EFI firmware switch to the integrated GPU > on boot by using this tool: https://github.com/0xbb/gpu-switch > However still both GPUs will be powered up, so you have to issue > the "OFF" command to sysfs to power the discrete GPU down. Also, > once you boot into OS X, the setting made by the gpu-switch tool > will be overwritten and the machine will be switched to the discrete > GPU again the next time you boot Linux. > > Note that switching is only possible from the text console, with > X11/Wayland shut down. Obviously this is not great in terms of UX. > A few years ago there was a GSoC proposal to get hot GPU switching > to work on Linux (akin to what OS X does) but nothing ever came of it: > http://www.phoronix.com/scan.php?page=news_item&px=OTIyMQ > https://lists.x.org/archives/xorg/2011-March/052522.html > > Unfortunately this seems to be a low priority item for kernel graphics > developers since nowadays most dual GPU notebooks no longer have a mux > and cannot switch. The MacBook Pro seems to be the last one supporting > this but I've witnessed a bit of an anti-Apple sentiment among kernel > graphics developers since everything is non-standard there. Which is > unfortunate because these machines have a large market share and Apple > software quality is deteriorating rapidly so a lot of Mac users are > ripe for converting to Linux. Is there any reason to make use of the mux? The usage model and amount of stack work for non-mux systems is a lot easier to deal with and covers a lot more systems overall. runtime pm generally works pretty seemlessly for mux-less systems. Properly handling the mux is a lot of work for relatively little gain as there are very few systems that use them. > > Anyway, one short-term improvement will be to add runtime pm support > (called "Driver power control" in the vga_switcheroo documentation > linked above). That way it'll no longer be necessary to power the > discrete GPU up and down manually, this will happen automatically > as needed (when switching or using render offloading with DRI PRIME). > I have patches to enable this for radeon but they're completely untested: > > http://wunner.de/mbp_switcheroo_v5-4.5.tar.gz => gpu switching for 4.5 > http://wunner.de/mbp_switcheroo_v5-4.5-runpm.tar.gz => runtime pm for radeon > > I have an Nvidia based machine and runtime pm doesn't work there yet > because of bugs in nouveau that I haven't had the time to look into. > > >> I did not use any external screens to test this. > > Since your machine has Thunderbolt, the external port is no longer > switchable between GPUs, it can only be driven by the discrete GPU. > So you need to power it up manually for this to work. You don't need > to switch to it, but it's probably recommendable to save energy. > (Otherwise both GPUs are on with the integrated GPU driving the panel > and the discrete GPU driving the DP port.) > > The runpm tarball linked above contains a patch to automatically > wake the discrete GPU on hotplug. > > I've heard that the AMD GPU is picky about external monitors and > doesn't recognize them unless they're plugged in at exactly the > right moment, so you may need to retry a couple of times until it > works. > Are talking about some issue specific to these muxed apple systems or in general? If you are having issues, please file a bug. Alex _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
