From: =?utf-8?q?Kristian_H=C3=B8gsberg?=, Stefan Richter Subject: firewire: Add a comment to describe why we split the sg list. Date: Wed, 9 May 2007 19:23:10 -0400 Signed-off-by: Kristian Hoegsberg Signed-off-by: Stefan Richter --- drivers/firewire/fw-sbp2.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) Index: linux/drivers/firewire/fw-sbp2.c =================================================================== --- linux.orig/drivers/firewire/fw-sbp2.c +++ linux/drivers/firewire/fw-sbp2.c @@ -926,7 +926,10 @@ static int sbp2_command_orb_map_scatterl /* * Convert the scatterlist to an sbp2 page table. If any - * scatterlist entries are too big for sbp2 we split the as we go. + * scatterlist entries are too big for sbp2, we split them as we + * go. Even if we ask the block I/O layer to not give us sg + * elements larger than 65535 bytes, some IOMMUs may merge sg elements + * during DMA mapping, and Linux currently doesn't prevent this. */ for (i = 0, j = 0; i < count; i++) { sg_len = sg_dma_len(sg + i);