On Thu, Jan 31, 2013 at 2:23 PM, Daniel Vetter <daniel@xxxxxxxx> wrote: > On Thu, Jan 31, 2013 at 9:38 AM, Rahul Sharma <r.sh.open@xxxxxxxxx> wrote: >> On Tue, Jan 29, 2013 at 10:40 PM, Aaron Plattner <aplattner@xxxxxxxxxx> wrote: >>> On 01/28/2013 05:38 AM, Rahul Sharma wrote: >>>> >>>> It fixes the issue arises due to passing 'nr_pages' in place of 'nents' to >>>> sg_alloc_table. When ARM_HAS_SG_CHAIN is disabled, it is causing failure >>>> in >>>> creating SG table for the buffers having more than 204 physical pages i.e. >>>> equal to SG_MAX_SINGLE_ALLOC. >>>> >>>> When using sg_alloc_table_from_pages interface, in place of >>>> sg_alloc_table, >>>> page list will be passes to get each contiguous section which is >>>> represented >>>> by a single entry in the table. For a Contiguous Buffer, number of entries >>>> should be equal to 1. >>>> >>>> Following check is causing the failure which is not applicable for >>>> Non-Contig >>>> buffers: >>>> >>>> if (WARN_ON_ONCE(nents > max_ents)) >>>> return -EINVAL; >>>> >>>> Above patch is well tested for EXYNOS4 and EXYNOS5 for with/wihtout IOMMU >>>> supprot. NOUVEAU and RADEON platforms also depends on >>>> drm_prime_pages_to_sg >>>> helper function. >>>> >>>> This set is base on "exynos-drm-fixes" branch at >>>> http://git.kernel.org/?p=linux/kernel/git/daeinki/drm-exynos.git >>>> >>>> Signed-off-by: Rahul Sharma <rahul.sharma@xxxxxxxxxxx> >>> >>> >>> Reviewed-by: Aaron Plattner <aplattner@xxxxxxxxxx> >>> >>> I also verified that this reduces my 2025-entry sg_table to 6 entries, so >>> >>> Tested-by: Aaron Plattner <aplattner@xxxxxxxxxx> >>> >>> -- >>> Aaron >>> >> >> Thanks Aaron, >> >> I want to request stake-holders to review and test this patch for >> other platforms. > > Iirc the old i915 dma_buf import code presumed that each sg entry > points to exactly one page. Yeah, Dave cut a few corners in the > initial implementation. Since Chris' rework to use sg_tables > internally in i915.ko I think we should be safe, but would need to do > a full audit of the code. No idea what the exact situation in ttm is. > > So I think step one is for you to crawl through the existing drm prime > drivers and check that you don't break any hidden assumptions about > this. Thanks Daniel, 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. > > 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. 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
