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authorAlan Stern <stern@rowland.harvard.edu>2008-11-21 11:46:17 -0500
committerGreg Kroah-Hartman <gregkh@suse.de>2009-01-07 09:59:57 -0800
commit96983d2d861bf94b7f70bc47ac3c5b289f519a2d (patch)
tree562c8f19df7dcf8bd2ad9a399e09fae71fcd8046 /drivers/usb/storage
parent3dae5345311271fe598a61bd01f563fc835b4217 (diff)
USB: storage: set bounce limit for non-DMA-capable host controllers
This patch (as1175) makes usb-storage set a SCSI device's request-queue bounce limit such that all buffers will be located in addressable memory (i.e., not in high memory) if the host controller's dma_mask is NULL. This is necessary when the host controller doesn't support DMA: If a buffer is in high memory then the both the virtual and DMA addresses produced by the scatter-gather library will be NULL, preventing the HCD from accessing the buffer's data. In particular, the isp1760 driver needs this when used on a system with more than 1 GB of memory. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> CC: Matthew Dharm <mdharm-usb@one-eyed-alien.net> Acked-by: Jens Axboe <jens.axboe@oracle.com> Tested-by: Thomas Hommel <Thomas.Hommel@gefanuc.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers/usb/storage')
-rw-r--r--drivers/usb/storage/scsiglue.c8
1 files changed, 8 insertions, 0 deletions
diff --git a/drivers/usb/storage/scsiglue.c b/drivers/usb/storage/scsiglue.c
index 1b35e011a34..e9d6c196a7a 100644
--- a/drivers/usb/storage/scsiglue.c
+++ b/drivers/usb/storage/scsiglue.c
@@ -129,6 +129,14 @@ static int slave_configure(struct scsi_device *sdev)
max_sectors);
}
+ /* Some USB host controllers can't do DMA; they have to use PIO.
+ * They indicate this by setting their dma_mask to NULL. For
+ * such controllers we need to make sure the block layer sets
+ * up bounce buffers in addressable memory.
+ */
+ if (!us->pusb_dev->bus->controller->dma_mask)
+ blk_queue_bounce_limit(sdev->request_queue, BLK_BOUNCE_HIGH);
+
/* We can't put these settings in slave_alloc() because that gets
* called before the device type is known. Consequently these
* settings can't be overridden via the scsi devinfo mechanism. */