RE: [PATCH v4 1/3] drm/prime: use dma length macro when mapping sg

[Ruhl, Michael J]

>-----Original Message-----
>From: dri-devel <dri-devel-bounces@xxxxxxxxxxxxxxxxxxxxx> On Behalf Of
>Shane Francis
>Sent: Wednesday, March 25, 2020 5:08 AM
>To: dri-devel@xxxxxxxxxxxxxxxxxxxxx
>Cc: airlied@xxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; bigbeeshane@xxxxxxxxx;
>amd-gfx-request@xxxxxxxxxxxxxxxxxxxxx; alexander.deucher@xxxxxxx;
>christian.koenig@xxxxxxx
>Subject: [PATCH v4 1/3] drm/prime: use dma length macro when mapping sg
>
>As dma_map_sg can reorganize scatter-gather lists in a
>way that can cause some later segments to be empty we should
>always use the sg_dma_len macro to fetch the actual length.
>
>This could now be 0 and not need to be mapped to a page or
>address array
>Signed-off-by: Shane Francis <bigbeeshane@xxxxxxxxx>
>---
> drivers/gpu/drm/drm_prime.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
>diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c
>index 86d9b0e45c8c..1de2cde2277c 100644
>--- a/drivers/gpu/drm/drm_prime.c
>+++ b/drivers/gpu/drm/drm_prime.c
>@@ -967,7 +967,7 @@ int drm_prime_sg_to_page_addr_arrays(struct
>sg_table *sgt, struct page **pages,
>
> 	index = 0;
> 	for_each_sg(sgt->sgl, sg, sgt->nents, count) {
>-		len = sg->length;
>+		len = sg_dma_len(sg);
> 		page = sg_page(sg);
> 		addr = sg_dma_address(sg);

This looks correct to me.

Reviewed-by: Michael J. Ruhl <michael.j.ruhl@xxxxxxxxx>

M

>
>--
>2.26.0
>
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