firewire: Add a comment to describe why we split the sg list.

Signed-off-by: Kristian Hoegsberg <krh@redhat.com>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
This commit is contained in:
Kristian Høgsberg, Stefan Richter 2007-05-09 19:23:10 -04:00 committed by Stefan Richter
parent e1b68c4dcf
commit 36abb3b18e

View File

@ -926,7 +926,10 @@ static int sbp2_command_orb_map_scatterlist(struct sbp2_command_orb *orb)
/*
* 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);