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| author | James Bottomley <James.Bottomley@HansenPartnership.com> | 2008-01-01 19:00:10 +0300 |
|---|---|---|
| committer | James Bottomley <James.Bottomley@HansenPartnership.com> | 2008-01-12 03:29:22 +0300 |
| commit | 465ff3185e0cb76d46137335a4d21d0d9d3ac8a2 (patch) | |
| tree | 171068cd7d99600cd094c2eb72bac712649fd9eb /drivers/ieee1394 | |
| parent | 11c3e689f1c3a73e3af7b0ea767b1b0626da8033 (diff) | |
| download | linux-465ff3185e0cb76d46137335a4d21d0d9d3ac8a2.tar.xz | |
[SCSI] relax scsi dma alignment
This patch relaxes the default SCSI DMA alignment from 512 bytes to 4
bytes. I remember from previous discussions that usb and firewire have
sector size alignment requirements, so I upped their alignments in the
respective slave allocs.
The reason for doing this is so that we don't get such a huge amount of
copy overhead in bio_copy_user() for udev. (basically all inquiries it
issues can now be directly mapped).
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Diffstat (limited to 'drivers/ieee1394')
| -rw-r--r-- | drivers/ieee1394/sbp2.c | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/drivers/ieee1394/sbp2.c b/drivers/ieee1394/sbp2.c index b83d254bc86e..1eda11abeb1e 100644 --- a/drivers/ieee1394/sbp2.c +++ b/drivers/ieee1394/sbp2.c @@ -1963,6 +1963,12 @@ static int sbp2scsi_slave_alloc(struct scsi_device *sdev) lu->sdev = sdev; sdev->allow_restart = 1; + /* + * Update the dma alignment (minimum alignment requirements for + * start and end of DMA transfers) to be a sector + */ + blk_queue_update_dma_alignment(sdev->request_queue, 511); + if (lu->workarounds & SBP2_WORKAROUND_INQUIRY_36) sdev->inquiry_len = 36; return 0; |