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When calculating the number of bounce pages needed, round the maxsize

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up to a multiple of PAGE_SIZE, and add one page because there can always
be one more boundary crossing than the number of pages in the transfer.
This commit is contained in:
ian 2013-10-16 16:32:35 +00:00
parent 5ac96cd6b7
commit 170337ca9d
1 changed files with 19 additions and 10 deletions
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29
sys/arm/arm/busdma_machdep-v6.c
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@ -425,14 +425,21 @@ bus_dma_tag_create(bus_dma_tag_t parent, bus_size_t alignment,
if (_bus_dma_can_bounce(newtag->lowaddr, newtag->highaddr)
|| newtag->alignment > 1)
newtag->flags |= BUS_DMA_COULD_BOUNCE;
else
maxsize = 2; /* Need at most 2 bounce pages for unaligned access on cache line boundaries */
/*
* Any request can auto-bounce due to cacheline alignment, in addition
* to any alignment or boundary specifications in the tag, so if the
* ALLOCNOW flag is set, there's always work to do.
*/
if ((flags & BUS_DMA_ALLOCNOW) != 0) {
struct bounce_zone *bz;
/* Must bounce */
/*
* Round size up to a full page, and add one more page because
* there can always be one more boundary crossing than the
* number of pages in a transfer.
*/
maxsize = roundup2(maxsize, PAGE_SIZE) + PAGE_SIZE;
if ((error = alloc_bounce_zone(newtag)) != 0) {
free(newtag, M_DEVBUF);
return (error);
@ -518,20 +525,22 @@ static int allocate_bz_and_pages(bus_dma_tag_t dmat, bus_dmamap_t mapp)
STAILQ_INIT(&(mapp->bpages));
/*
* Attempt to add pages to our pool on a per-instance
* basis up to a sane limit.
* Attempt to add pages to our pool on a per-instance basis up to a sane
* limit. Even if the tag isn't flagged as COULD_BOUNCE due to
* alignment and boundary constraints, it could still auto-bounce due to
* cacheline alignment, which requires at most two bounce pages.
*/
if (dmat->flags & BUS_DMA_COULD_BOUNCE)
maxpages = MAX_BPAGES;
else
maxpages = 2 * bz->map_count; /* Only need at most 2 pages for buffers unaligned on cache line boundaries */
maxpages = 2 * bz->map_count;
if ((dmat->flags & BUS_DMA_MIN_ALLOC_COMP) == 0
|| (bz->map_count > 0 && bz->total_bpages < maxpages)) {
int pages;
pages = MAX(atop(dmat->maxsize), 1);
pages = atop(roundup2(dmat->maxsize, PAGE_SIZE)) + 1;
pages = MIN(maxpages - bz->total_bpages, pages);
pages = MAX(pages, 1);
pages = MAX(pages, 2);
if (alloc_bounce_pages(dmat, pages) < pages)
return (ENOMEM);