On Wed, 26 Sep 2007 06:11:45 -0400 Jeff Garzik <jeff@xxxxxxxxxx> wrote: > FUJITA Tomonori wrote: > > This patch moves blk_queue_max_segment_size to scsi_alloc_queue from > > llds. It enables scsi_add_host to tells iommu lld's > > dma_max_segment_size. If a low-level driver doesn't specify > > dma_max_segment_size, scsi-ml uses 65536 (MAX_SEGMENT_SIZE). So there > > are not any functional changes. > > > > Signed-off-by: FUJITA Tomonori <fujita.tomonori@xxxxxxxxxxxxx> > > --- > > drivers/scsi/hosts.c | 5 +++++ > > drivers/scsi/scsi_lib.c | 1 + > > include/scsi/scsi_host.h | 6 ++++++ > > 3 files changed, 12 insertions(+), 0 deletions(-) > > hmmmmm... All the patches look technically correct, but IMO this really > should behave more the the dma_mask interface: platform sets a sane > dma_mask (usually 0xffffffff), and LLDD calls dma_set_mask() or > pci_set_dma_mask(). > > Thus, IMO an LLDD should call dma_set_max_seg(), and then SCSI midlayer > can obtain that value from struct device. Yeah, I agreed that max_segment_size should work like dma_mask (that's why I simply put max_segment_size to device structure). scsi_debug doesn't use dma but calls blk_queue_max_segment_size (I guess that it wants large I/Os). If we can remove it (thanks to chaining sg), scsi-ml gets that value that llds set via dma_set_max_seg and calls blk_queue_max_segment_size. - To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
