From d46e7ae24b81533d21edfa90914d27efa0c5f85d Mon Sep 17 00:00:00 2001 From: Marek Szyprowski Date: Fri, 8 May 2020 16:04:44 +0200 Subject: drm: prime: add common helper to check scatterlist contiguity It is a common operation done by DRM drivers to check the contiguity of the DMA-mapped buffer described by a scatterlist in the sg_table object. Let's add a common helper for this operation. Signed-off-by: Marek Szyprowski Reviewed-by: Andrzej Hajda Reviewed-by: Robin Murphy --- drivers/gpu/drm/drm_prime.c | 31 +++++++++++++++++++++++++++++++ 1 file changed, 31 insertions(+) (limited to 'drivers/gpu/drm/drm_prime.c') diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c index 1693aa7c14b5..4ed5ed1f078c 100644 --- a/drivers/gpu/drm/drm_prime.c +++ b/drivers/gpu/drm/drm_prime.c @@ -825,6 +825,37 @@ out: } EXPORT_SYMBOL(drm_prime_pages_to_sg); +/** + * drm_prime_get_contiguous_size - returns the contiguous size of the buffer + * @sgt: sg_table describing the buffer to check + * + * This helper calculates the contiguous size in the DMA address space + * of the the buffer described by the provided sg_table. + * + * This is useful for implementing + * &drm_gem_object_funcs.gem_prime_import_sg_table. + */ +unsigned long drm_prime_get_contiguous_size(struct sg_table *sgt) +{ + dma_addr_t expected = sg_dma_address(sgt->sgl); + struct scatterlist *sg; + unsigned long size = 0; + int i; + + for_each_sgtable_dma_sg(sgt, sg, i) { + unsigned int len = sg_dma_len(sg); + + if (!len) + break; + if (sg_dma_address(sg) != expected) + break; + expected += len; + size += len; + } + return size; +} +EXPORT_SYMBOL(drm_prime_get_contiguous_size); + /** * drm_gem_prime_export - helper library implementation of the export callback * @obj: GEM object to export -- cgit v1.2.3