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-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. */