1 files changed, 28 insertions, 0 deletions

diff --git a/lib/dma-debug.c b/lib/dma-debug.c
index 6a1ebaa83623..c007d25bee09 100644
--- a/lib/dma-debug.c
+++ b/lib/dma-debug.c
@@ -1286,6 +1286,32 @@ out:
         put_hash_bucket(bucket, &flags);
 }
 
+static void check_sg_segment(struct device *dev, struct scatterlist *sg)
+{
+#ifdef CONFIG_DMA_API_DEBUG_SG
+        unsigned int max_seg = dma_get_max_seg_size(dev);
+        u64 start, end, boundary = dma_get_seg_boundary(dev);
+
+        /*
+         * Either the driver forgot to set dma_parms appropriately, or
+         * whoever generated the list forgot to check them.
+         */
+        if (sg->length > max_seg)
+                err_printk(dev, NULL, "DMA-API: mapping sg segment longer than device claims to support [len=%u] [max=%u]\n",
+                           sg->length, max_seg);
+        /*
+         * In some cases this could potentially be the DMA API
+         * implementation's fault, but it would usually imply that
+         * the scatterlist was built inappropriately to begin with.
+         */
+        start = sg_dma_address(sg);
+        end = start + sg_dma_len(sg) - 1;
+        if ((start ^ end) & ~boundary)
+                err_printk(dev, NULL, "DMA-API: mapping sg segment across boundary [start=0x%016llx] [end=0x%016llx] [boundary=0x%016llx]\n",
+                           start, end, boundary);
+#endif
+}
+
 void debug_dma_map_page(struct device *dev, struct page *page, size_t offset,
                         size_t size, int direction, dma_addr_t dma_addr,
                         bool map_single)
@@ -1416,6 +1442,8 @@ void debug_dma_map_sg(struct device *dev, struct scatterlist *sg,
                         check_for_illegal_area(dev, sg_virt(s), sg_dma_len(s));
                 }
 
+                check_sg_segment(dev, s);
+
                 add_dma_entry(entry);
         }
 }