On Fri, 28 Feb 2014 16:43:54 +0100 Christian König <deathsimple@xxxxxxxxxxx> wrote: > >>> Am 27.02.2014 22:38, schrieb Lauri Kasanen: > >>>> Without this, a bo may get created in the cpu-inaccessible vram. > >>>> Before the CP engines get setup, all copies are done via cpu memcpy. > >>>> > >>>> This means that the cpu tries to read from inaccessible memory, fails, > >>>> and the radeon module proceeds to disable acceleration. > >>>> > >>>> Doing this has no downsides, as the real VRAM size gets set as soon as the > >>>> CP engines get init. > >>>> > >>>> This is a candidate for 3.14 fixes. > >>> This should be unnecessary, since TTM gets initialized only seeing the > >>> visible VRAM and later on radeon_ttm_set_active_vram_size gets called to > >>> increase the limit. > >>> > >>> If this isn't the case any more we should figure out why instead of > >>> working around it like this. > >> Negative, TTM gets initialized with real_vram just a few lines above > >> this patch, not visible_vram. > > git blame shows 7a50f01a from 2009, "drm/radeon/kms: vram sizing on > > certain r100 chips needs workaround." by Dave Airlie. > > > > So the TTM VRAM init has been wrong for five years, and only worked by > > accident because until now all allocations were done bottom-up. > > Yeah, just came to the same conclusion. We probably never hit the case > in the last five years because we don't really access the memory before > we start the copy ring. > > Please fix ttm_bo_init_mm to use rdev->mc.visible_vram_size instead. > > That allocations are made bottom-up is relied upon in a couple of other > cases as well, the stolen VGA memory and the UVD firmware handling for > example. I initially did that, but it caused some issues. I didn't investigage it further, but I guess it has to be init to the maximum size, and then only the size lowered, so that the change only affects lpfn. - Lauri _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/dri-devel
