On Tue, Feb 27, 2018 at 12:49:57PM +0100, Christian König wrote:
> Most of the time we only need the dma addresses.
>
> Signed-off-by: Christian König <christian.koenig@xxxxxxx>
> ---
> drivers/gpu/drm/drm_prime.c | 20 ++++++++++----------
> 1 file changed, 10 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c
> index c38dacda6119..7856a9b3f8a8 100644
> --- a/drivers/gpu/drm/drm_prime.c
> +++ b/drivers/gpu/drm/drm_prime.c
> @@ -922,40 +922,40 @@ EXPORT_SYMBOL(drm_prime_pages_to_sg);
> /**
> * drm_prime_sg_to_page_addr_arrays - convert an sg table into a page array
> * @sgt: scatter-gather table to convert
> - * @pages: array of page pointers to store the page array in
> + * @pages: optional array of page pointers to store the page array in
> * @addrs: optional array to store the dma bus address of each page
> - * @max_pages: size of both the passed-in arrays
> + * @max_entries: size of both the passed-in arrays
> *
> * Exports an sg table into an array of pages and addresses. This is currently
> * required by the TTM driver in order to do correct fault handling.
> */
Can't we just teach ttm to use sgts wherever needed, and deprecate
exporting dma-bufs to page arrays (which really breaks the abstraction
entirely and was just a quick hack to get things going that stuck around
for years). Last time I looked into ttm the only thing it did is convert
it back to sgts again (after calling dma_map once more, which the exporter
should have done already for you).
-Daniel
> int drm_prime_sg_to_page_addr_arrays(struct sg_table *sgt, struct page **pages,
> - dma_addr_t *addrs, int max_pages)
> + dma_addr_t *addrs, int max_entries)
> {
> unsigned count;
> struct scatterlist *sg;
> struct page *page;
> - u32 len;
> - int pg_index;
> + u32 len, index;
> dma_addr_t addr;
>
> - pg_index = 0;
> + index = 0;
> for_each_sg(sgt->sgl, sg, sgt->nents, count) {
> len = sg->length;
> page = sg_page(sg);
> addr = sg_dma_address(sg);
>
> while (len > 0) {
> - if (WARN_ON(pg_index >= max_pages))
> + if (WARN_ON(index >= max_entries))
> return -1;
> - pages[pg_index] = page;
> + if (pages)
> + pages[index] = page;
> if (addrs)
> - addrs[pg_index] = addr;
> + addrs[index] = addr;
>
> page++;
> addr += PAGE_SIZE;
> len -= PAGE_SIZE;
> - pg_index++;
> + index++;
> }
> }
> return 0;
> --
> 2.14.1
>
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--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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