On Thu, 10 May 2012 00:40:20 +0200 Daniel Vetter <daniel.vetter at ffwll.ch> wrote: > Inspired by the recent ppgtt regression report, where switching of > dmar only for the gpu seems to fix things completely, I've looked > again at the semaphores+vt-d situation. > > Contrary to my earlier testing a few months back my system is now > stable with dmar disabled for the igd, and not only when disabling > dmar completely. > > So I'm rather hopeful that all our recent fixes for snb have changed > things for code and it's time to try enabling semaphores again. We've > also had issues with enabling semaphores which are not vt-d related, > but I guess these are all fixed by the autoreport-disabling and lazy > request fix. And there's only one way to find out whether there are > still other issues ... > > When I've tried to apply this patch I've noticed that semaphores on > gen6 have already silently been added in > > commit 2911a35b2e4eb87ec48d03aeb11f019e51ae3c0d > Author: Ben Widawsky <ben at bwidawsk.net> > Date: Thu Apr 5 14:47:36 2012 -0700 > > drm/i915: use semaphores for the display plane > > Fix this up by only checking whether dmar is enabled on the gfx (not > on the entire system). Heh. It wasn't on purpose! I want to blame this on git, but I honestly don't know what happened. > > Cc: Ben Widawsky <ben at bwidawsk.net> > Cc: Chris Wilson <chris at chris-wilson.co.uk> > Signed-Off-by: Daniel Vetter <daniel.vetter at ffwll.ch> Reviewed-by: Ben Widawsky <ben at bwidawsk.net> > --- > drivers/gpu/drm/i915/i915_drv.c | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c > index 77b7a50..1ccfc23 100644 > --- a/drivers/gpu/drm/i915/i915_drv.c > +++ b/drivers/gpu/drm/i915/i915_drv.c > @@ -407,9 +407,11 @@ bool i915_semaphore_is_enabled(struct drm_device *dev) > if (i915_semaphores >= 0) > return i915_semaphores; > > +#ifdef CONFIG_INTEL_IOMMU > /* Enable semaphores on SNB when IO remapping is off */ > - if (INTEL_INFO(dev)->gen == 6) > - return !intel_iommu_enabled; > + if (INTEL_INFO(dev)->gen == 6 && intel_iommu_gfx_mapped) > + return false; > +#endif > > return 1; > } -- Ben Widawsky, Intel Open Source Technology Center
