On Fri, Aug 9, 2013 at 11:36 AM, Daniel Vetter <daniel.vetter@xxxxxxxx> wrote: > On Fri, Aug 9, 2013 at 8:12 PM, Andy Lutomirski <luto@xxxxxxxxxxxxxx> wrote: >> On Thu, Aug 8, 2013 at 6:41 AM, Daniel Vetter <daniel.vetter@xxxxxxxx> wrote: >>> The new arch_phys_wc_add/del functions do the right thing both with >>> and without MTRR support in the kernel. So we can drop these >>> additional checks. >> >> If any of the new arch_phys_wc_add calls are reachable and if the >> driver calls arch_phys_wc_add itself, then the lack of refcounting on >> non-PAT systems may cause a problem. (I don't understand the drm >> stuff well enough to know whether that can actually happen.) > > This is only about compile-time options really. Somehow drm had the > idea to use these check functions instead of #ifdef plus dummy static > inline noop functions. David Herrmann just did the same patch for the > agp stuff. So refcounting is of no concern here. I feel like I'm missing something obvious here. On nouveau, prior to this patch, the drm maps code would not touch mtrrs. Now it will. Nouveau already calls arch_phys_wc_add, so if that maps code is reached on the same resource, then there could be refcounting issues. --Andy > -Daniel > -- > Daniel Vetter > Software Engineer, Intel Corporation > +41 (0) 79 365 57 48 - http://blog.ffwll.ch -- Andy Lutomirski AMA Capital Management, LLC _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/dri-devel
