This patch fixes the problem of mapping gem objects which are non-contigous dma buffers. These buffers are described using SG table and SG lists. Each valid SG List is pointing to a single page or group of pages which are physically contigous.

Current implementation just maps the first page of each SG List and leave the other pages unmapped, leading to a crash.

Given solution finds the page struct for the faulting page through parsing SG table and map it.

This patch is based on branch exynos-drm-next-iommu at git://git.kernel.org/pub/scm/linux/kernel/git/daeinki/drm-exynos.git

v1: 1) instead of mapping whole section, mapping single page.

Signed-off-by: Rahul Sharma rahul.sharma@samsung.com --- drivers/gpu/drm/exynos/exynos_drm_gem.c | 22 ++++++++++++++++++++-- 1 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/exynos/exynos_drm_gem.c b/drivers/gpu/drm/exynos/exynos_drm_gem.c index 8cb6824..c557ac7 100644 --- a/drivers/gpu/drm/exynos/exynos_drm_gem.c +++ b/drivers/gpu/drm/exynos/exynos_drm_gem.c @@ -95,13 +95,31 @@ static int exynos_drm_gem_map_buf(struct drm_gem_object *obj, { struct exynos_drm_gem_obj *exynos_gem_obj = to_exynos_gem_obj(obj); struct exynos_drm_gem_buf *buf = exynos_gem_obj->buffer; + struct scatterlist *sgl; unsigned long pfn; + int i;

if (exynos_gem_obj->flags & EXYNOS_BO_NONCONTIG) { - if (!buf->pages) + if (!buf->sgt) return -EINTR;

- pfn = page_to_pfn(buf->pages[page_offset++]); + sgl = buf->sgt->sgl; + for_each_sg(buf->sgt->sgl, sgl, buf->sgt->nents, i) { + if (!sgl) { + DRM_ERROR("invalid SG table\n"); + return -EINTR; + } + if (page_offset < (sgl->length >> PAGE_SHIFT)) + break; + page_offset -= (sgl->length >> PAGE_SHIFT); + } + + if (i >= buf->sgt->nents) { + DRM_ERROR("invalid page offset\n"); + return -EINVAL; + } + + pfn = __phys_to_pfn(sg_phys(sgl)) + page_offset; } else pfn = (buf->dma_addr >> PAGE_SHIFT) + page_offset;