On Thu, Jan 31, 2013 at 5:47 PM, Daniel Vetter <daniel@xxxxxxxx> wrote: > On Thu, Jan 31, 2013 at 12:54 PM, Rahul Sharma <r.sh.open@xxxxxxxxx> wrote: >> I have parsed the related code and it looks fine to me. I couldn't find >> any code section, expecting sg-tables with single-page sgl entries. I >> just want to ensure again that it doesn't cause any side effects on >> various platforms. > > Just chatted with Chris Wilson on our team, and at last i915.ko _has_ > code paths which rely on this. See the reloc handling offset > computations in i915_gem_execbuf.c. I haven't checked > ttm/radeon/nouveau/vmwgfx simply because I don't have the time right > now, and I know that doing this carefully will blow through a few > days. So this patch will break prime buffer sharing on the desktop. > > The other thing is that only doing sg entry coalescing for > prime/dma_buf will lead to a QA problem, since all the normal sg > tables still have a 1:1 relationship. So imo the right way to move > forward with this is to convert the various sg table constructors in > i915/ttm/radeon/nouveau/... over to coalesce pages. This allows us to > fix any fallout step-by-step. > > Then, once each driver is ready for this, we can merge your patch. > Looks fine to me. >>> For the patch itself I think there's now a generic pages_to_sg helper >>> in the dma core which does exactly what you want it to do. I can dig >>> it out if you can't find it. >>> >> >> Sorry, I din't get this part. Please elaborate a bit. > > See sg_alloc_table_from_pages in lib/scatterlist.c introduced with: > > commit efc42bc98058a36d761b16a114823db1a902ed05 > Author: Tomasz Stanislawski <t.stanislaws@xxxxxxxxxxx> > Date: Mon Jun 18 09:25:01 2012 +0200 > > scatterlist: add sg_alloc_table_from_pages function > Yes, my patch is using sg_alloc_table_from_pages. regards, Rahul Sharma. > Cheers, Daniel > -- > Daniel Vetter > Software Engineer, Intel Corporation > +41 (0) 79 365 57 48 - http://blog.ffwll.ch _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/dri-devel
