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authorJames Bottomley <James.Bottomley@HansenPartnership.com>2008-01-01 10:00:10 -0600
committerJames Bottomley <James.Bottomley@HansenPartnership.com>2008-01-11 18:29:22 -0600
commit465ff3185e0cb76d46137335a4d21d0d9d3ac8a2 (patch)
tree171068cd7d99600cd094c2eb72bac712649fd9eb /drivers/ata
parent11c3e689f1c3a73e3af7b0ea767b1b0626da8033 (diff)
downloadop-kernel-dev-465ff3185e0cb76d46137335a4d21d0d9d3ac8a2.zip
op-kernel-dev-465ff3185e0cb76d46137335a4d21d0d9d3ac8a2.tar.gz
[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/ata')
-rw-r--r--drivers/ata/libata-scsi.c5
1 files changed, 4 insertions, 1 deletions
diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index 264ae60..4bb268b 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -824,6 +824,9 @@ static void ata_scsi_sdev_config(struct scsi_device *sdev)
* requests.
*/
sdev->max_device_blocked = 1;
+
+ /* set the min alignment */
+ blk_queue_update_dma_alignment(sdev->request_queue, ATA_DMA_PAD_SZ - 1);
}
static void ata_scsi_dev_config(struct scsi_device *sdev,
@@ -878,7 +881,7 @@ int ata_scsi_slave_config(struct scsi_device *sdev)
if (dev)
ata_scsi_dev_config(sdev, dev);
- return 0; /* scsi layer doesn't check return value, sigh */
+ return 0;
}
/**
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