iommu sg merging: parisc: make iommu respect the segment size limits

This patch makes iommu respect segment size limits when merging sg
lists.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: Jeff Garzik <jeff@garzik.org>
Cc: James Bottomley <James.Bottomley@steeleye.com>
Acked-by: Jens Axboe <jens.axboe@oracle.com>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Acked-by: Grant Grundler <grundler@parisc-linux.org>
Cc: Matthew Wilcox <willy@debian.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 8 insertions, 3 deletions

diff --git a/drivers/parisc/ccio-dma.c b/drivers/parisc/ccio-dma.c
index ca52307b8f40..d08b284de196 100644
--- a/drivers/parisc/ccio-dma.c
+++ b/drivers/parisc/ccio-dma.c
@@ -941,7 +941,7 @@ ccio_map_sg(struct device *dev, struct scatterlist *sglist, int nents,
         ** w/o this association, we wouldn't have coherent DMA!
         ** Access to the virtual address is what forces a two pass algorithm.
         */
-        coalesced = iommu_coalesce_chunks(ioc, sglist, nents, ccio_alloc_range);
+        coalesced = iommu_coalesce_chunks(ioc, dev, sglist, nents, ccio_alloc_range);
 
         /*
         ** Program the I/O Pdir
diff --git a/drivers/parisc/iommu-helpers.h b/drivers/parisc/iommu-helpers.h
index 0a1f99a2e93e..97ba8286c596 100644
--- a/drivers/parisc/iommu-helpers.h
+++ b/drivers/parisc/iommu-helpers.h
@@ -95,12 +95,14 @@ iommu_fill_pdir(struct ioc *ioc, struct scatterlist *startsg, int nents,
 */
 
 static inline unsigned int
-iommu_coalesce_chunks(struct ioc *ioc, struct scatterlist *startsg, int nents,
+iommu_coalesce_chunks(struct ioc *ioc, struct device *dev,
+                      struct scatterlist *startsg, int nents,
                       int (*iommu_alloc_range)(struct ioc *, size_t))
 {
         struct scatterlist *contig_sg;     /* contig chunk head */
         unsigned long dma_offset, dma_len; /* start/len of DMA stream */
         unsigned int n_mappings = 0;
+        unsigned int max_seg_size = dma_get_max_seg_size(dev);
 
         while (nents > 0) {
 
@@ -142,6 +144,9 @@ iommu_coalesce_chunks(struct ioc *ioc, struct scatterlist *startsg, int nents,
                                             IOVP_SIZE) > DMA_CHUNK_SIZE))
                                 break;
 
+                        if (startsg->length + dma_len > max_seg_size)
+                                break;
+
                         /*
                         ** Next see if we can append the next chunk (i.e.
                         ** it must end on one page and begin on another
diff --git a/drivers/parisc/sba_iommu.c b/drivers/parisc/sba_iommu.c
index e527a0e1d6c0..d06627c3f353 100644
--- a/drivers/parisc/sba_iommu.c
+++ b/drivers/parisc/sba_iommu.c
@@ -946,7 +946,7 @@ sba_map_sg(struct device *dev, struct scatterlist *sglist, int nents,
         ** w/o this association, we wouldn't have coherent DMA!
         ** Access to the virtual address is what forces a two pass algorithm.
         */
-        coalesced = iommu_coalesce_chunks(ioc, sglist, nents, sba_alloc_range);
+        coalesced = iommu_coalesce_chunks(ioc, dev, sglist, nents, sba_alloc_range);
 
         /*
         ** Program the I/O Pdir