On Tue, Dec 13, 2011 at 09:20:40AM -0800, Eric Anholt wrote: > On Tue, 13 Dec 2011 17:09:37 +0100, Daniel Vetter <daniel at ffwll.ch> wrote: > > On Tue, Dec 13, 2011 at 11:05:15AM -0200, Eugeni Dodonov wrote: > > > From: Eugeni Dodonov <eugeni.dodonov at intel.com> > > > > > > LLC is not SNB-specific, so we should check for it in a more generic way. > > > > > > v2: export LLC support status via debugfs and DRM GETPARAM. > > > > > > Signed-off-by: Eugeni Dodonov <eugeni.dodonov at intel.com> > > > > Nice patch and would get an r-b from me safe for the new GETPARAM. I > > really think we need to export this on a per-bo basis (and with the caveat > > that the kernel is free to change the caching on every ioctl that uses > > it). I.e. without forcing userspace to check the caching bits before any > > bo access I fear that we won't be able to change the kernel's behaviour in > > this area, which surely results in backwards-compat hell when the first > > w/a that needs such changes comes around. Hence in its current from > > > > Nacked-by: Daniel Vetter <daniel.vetter at ffwll.ch> > > > > So please drop the GETPARAM. For the per-bo get_cache_flags ioctl there's > > already a patch by Ben floating around. > > The way the getparam would be useful is that right now we're taking some > different paths for performance reasons in Mesa on gen6, assuming that > LLC is present. Knowing whether or not we expect BOs in general to be > LLC for performance would be nice for that -- without that, I'll just > make assumptions based on chipset generation. Ok, I'll reconsider: In the mesa example (and any other use-case for llc accelarated up/download) we don't depend upon llc for correctness and we're using the caching on a newly created buffer, so the per-bo ioctls aren't much use. So I think the backwards-compat mess is manageable if people promise to use the HAS_LLC getparam only for such optimizations ... I still think we want to full get/set_cache_level in additions to this. But for this patch: Reviewed-by: Daniel Vetter <daniel.vetter at ffwll.ch> -- Daniel Vetter Mail: daniel at ffwll.ch Mobile: +41 (0)79 365 57 48
