On 29 November 2015 at 12:47, Daniel Vetter <daniel@xxxxxxxx> wrote: > On Fri, Nov 27, 2015 at 07:37:53PM -0500, Ilia Mirkin wrote: >> On Fri, Nov 27, 2015 at 10:40 AM, Emil Velikov <emil.l.velikov@xxxxxxxxx> wrote: >> > On 27 November 2015 at 15:10, Daniel Vetter <daniel.vetter@xxxxxxxx> wrote: >> >> It only leads to bloodshed and tears - we don't bother to restore a >> >> working legacy vga hw setup. >> >> >> >> On haswell with the new dynamic power well code this leads to even >> >> more hilarity since for some configurations the hardware is simply no >> >> longer there. >> >> >> >> The actual implementation is a bit a hack - we realy on fbcon to kick >> >> out the vgacon. To make this also work with I915_FBDEV=n (or FBCON=n) >> >> and VGA_CONSOLE=y i915 already unregisters the vga console manually >> >> early in the driver load sequence. >> >> >> > Interesting... nv50 and later GPUs are in a roughly similar shame >> > afaict. They lack the dedicated hardware and no one really bothered >> > figuring out how to restore things to a working shape [1]. >> > >> > Then again, upon sequential load of the nouveau module the GPU gets >> > initialised properly, where you can get X (weston?) up and running >> > without issues. Am I thinking about a different thing ? >> > >> > I take it that you guys do less of the (re)initialisation dance, to >> > ensure faster boot times ? >> > >> > Thanks, >> > Emil >> > >> > [1] http://nouveau.freedesktop.org/wiki/KernelModeSetting/#deactivatingkmsandunloadingnouveau >> >> FWIW it's possible to unload nouveau, at which point your screen turns >> off (because we can't restore the vga emulation junk... haven't the >> faintest clue how it works), and then reload it, at which point fbcon >> gets rebound and is completely happy. I can't tell what this patch is >> doing, but for your own sanity, you should support unloading/reloading >> i915 as well. > > We do of course support unloading/reloading. And we do the same "shut > everything down" like nouveau seems to do. The problem though on some hw > is that if vgacon then tries to access the registers the hw dies. So the > problem we have with not restoring VGA functionality isn't that the screen > is black when i915.ko is unloaded, but that the machine dies. This patch > fixes that. I see. Thank you for the explanation! -Emil _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
