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. 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. 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
