From 465ff3185e0cb76d46137335a4d21d0d9d3ac8a2 Mon Sep 17 00:00:00 2001 From: James Bottomley Date: Tue, 1 Jan 2008 10:00:10 -0600 Subject: [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 Signed-off-by: James Bottomley --- drivers/ata/libata-scsi.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'drivers/ata') diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c index 264ae60e3fd..4bb268b9aae 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; } /** -- cgit v1.2.3-70-g09d2