x86-64: pci-gart iommu uses max_segment_size

index 4918c57..be98341 100644
@@ -381,6 +381,7 @@ int gart_map_sg(struct device *dev, struct scatterlist *sg, int nents, int dir)
 	int start;
 	unsigned long pages = 0;
 	int need = 0, nextneed;
+	unsigned len;
 
 	if (nents == 0) 
 		return 0;

@@ -390,6 +391,7 @@ int gart_map_sg(struct device *dev, struct scatterlist *sg, int nents, int dir)
 
 	out = 0;
 	start = 0;
+	len = 0;
 	for (i = 0; i < nents; i++) {
 		struct scatterlist *s = &sg[i];
 		dma_addr_t addr = page_to_phys(s->page) + s->offset;

@@ -404,16 +406,20 @@ int gart_map_sg(struct device *dev, struct scatterlist *sg, int nents, int dir)
 			/* Can only merge when the last chunk ends on a page 
 			   boundary and the new one doesn't have an offset. */
 			if (!iommu_merge || !nextneed || !need || s->offset ||
+			    (dev->max_segment_size &&
+			     dev->max_segment_size < s->length + len) ||
 			    (ps->offset + ps->length) % PAGE_SIZE) { 
 				if (dma_map_cont(sg, start, i, sg+out, pages,
 						 need) < 0)
 					goto error;
 				out++;
+				len = 0;
 				pages = 0;
 				start = i;	
 			}
 		}
 
+		len += s->length;
 		need = nextneed;
 		pages += to_pages(s->offset, s->length);
 	}