Hi Tomasz,
Thanks for the patch.
On Friday 13 April 2012 17:47:50 Tomasz Stanislawski wrote:
From: Andrzej Pietrasiewicz andrzej.p@samsung.com
This patch introduces usage of dma_map_sg to map memory behind a userspace pointer to a device as dma-contiguous mapping.
Signed-off-by: Andrzej Pietrasiewicz andrzej.p@samsung.com Signed-off-by: Marek Szyprowski m.szyprowski@samsung.com [bugfixing] Signed-off-by: Kamil Debski k.debski@samsung.com [bugfixing] Signed-off-by: Tomasz Stanislawski t.stanislaws@samsung.com [add sglist subroutines/code refactoring] Signed-off-by: Kyungmin Park kyungmin.park@samsung.com
drivers/media/video/videobuf2-dma-contig.c | 287 +++++++++++++++++++++++-- 1 files changed, 270 insertions(+), 17 deletions(-)
diff --git a/drivers/media/video/videobuf2-dma-contig.c b/drivers/media/video/videobuf2-dma-contig.c index 476e536..3a1e314 100644 --- a/drivers/media/video/videobuf2-dma-contig.c +++ b/drivers/media/video/videobuf2-dma-contig.c
[snip]
+static struct sg_table *vb2_dc_pages_to_sgt(struct page **pages,
- unsigned int n_pages, unsigned long offset, unsigned long size)
+{
- struct sg_table *sgt;
- unsigned int chunks;
- unsigned int i;
- unsigned int cur_page;
- int ret;
- struct scatterlist *s;
- unsigned int offset_end = n_pages * PAGE_SIZE - size;
Shouldn't offset_end be equal to n_page * PAGE_SIZE - size - offset ?
- sgt = kzalloc(sizeof *sgt, GFP_KERNEL);
- if (!sgt)
return ERR_PTR(-ENOMEM);- /* compute number of chunks */
- chunks = 1;
- for (i = 1; i < n_pages; ++i)
if (pages[i] != pages[i - 1] + 1)++chunks;- ret = sg_alloc_table(sgt, chunks, GFP_KERNEL);
- if (ret) {
kfree(sgt);return ERR_PTR(-ENOMEM);- }
- /* merging chunks and putting them into the scatterlist */
- cur_page = 0;
- for_each_sg(sgt->sgl, s, sgt->orig_nents, i) {
size_t size = PAGE_SIZE;
This will shadow the size parameter, it's a bit confusing. You could rename it chunk_size.
unsigned int j;for (j = cur_page + 1; j < n_pages; ++j) {if (pages[j] != pages[j - 1] + 1)break;size += PAGE_SIZE;}
/* cut offset if chunk starts at the first page */if (cur_page == 0)size -= offset;/* cut offset_end if chunk ends at the last page */if (j == n_pages)size -= offset_end;sg_set_page(s, pages[cur_page], size, offset);offset = 0;
What about just
chunk_size -= offset; sg_set_page(s, pages[cur_page], min(size, chunk_size), offset); size -= chunk_size; offset = 0;
You could then remove the offset_end calculation above.
cur_page = j;- }
- return sgt;
+}