[PATCHv4 2/3] usb: storage: scsiglue: limit USB3 devices to 2048 sectors

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USB3 devices, because they are much newer, have much
less chance of having issues with larger transfers.

We still keep a limit because anything above 2048
sectors really rendered negligible speed
improvements, so we will simply ignore
that. Transferring 1MiB should already give us
pretty good performance.

Signed-off-by: Felipe Balbi <felipe.balbi@xxxxxxxxxxxxxxx>
---
 drivers/usb/storage/scsiglue.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/usb/storage/scsiglue.c b/drivers/usb/storage/scsiglue.c
index 9da1fb3d0ff4..2bb6a88858ea 100644
--- a/drivers/usb/storage/scsiglue.c
+++ b/drivers/usb/storage/scsiglue.c
@@ -127,6 +127,11 @@ static int slave_configure(struct scsi_device *sdev)
 		if (queue_max_hw_sectors(sdev->request_queue) > max_sectors)
 			blk_queue_max_hw_sectors(sdev->request_queue,
 					      max_sectors);
+	} else if (us->pusb_dev->speed >= USB_SPEED_SUPER) {
+		/* USB3 devices will be limited to 2048 sectors. This gives us
+		 * better throughput on most devices.
+		 */
+		blk_queue_max_hw_sectors(sdev->request_queue, 2048);
 	} else if (sdev->type == TYPE_TAPE) {
 		/* Tapes need much higher max_sector limits, so just
 		 * raise it to the maximum possible (4 GB / 512) and
-- 
2.8.0.rc2

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