When the scsi request queue is initialized/allocated, the scsi driver clamps
hw_max_sectors against the dma max mapping size of sdev->host->dma_dev. The
device is currently inappriorate to use for USB drives.
Therefore, always (re)set hw_max_sectors in the usb drivers to invalidate the
clamping.
Signed-off-by: Tom Yan <tom.ty89@xxxxxxxxx>
---
drivers/usb/storage/scsiglue.c | 37 ++++++++++++++++------------------
drivers/usb/storage/uas.c | 2 ++
2 files changed, 19 insertions(+), 20 deletions(-)
diff --git a/drivers/usb/storage/scsiglue.c b/drivers/usb/storage/scsiglue.c
index e5a971b83e3f..1f60d777a7e8 100644
--- a/drivers/usb/storage/scsiglue.c
+++ b/drivers/usb/storage/scsiglue.c
@@ -120,6 +120,23 @@ static int slave_configure(struct scsi_device *sdev)
* better throughput on most devices.
*/
blk_queue_max_hw_sectors(sdev->request_queue, 2048);
+ } else {
+ /*
+ * Some devices are known to choke with anything larger. It seems like
+ * the problem stems from the fact that original IDE controllers had
+ * only an 8-bit register to hold the number of sectors in one transfer
+ * and even those couldn't handle a full 256 sectors.
+ *
+ * Because we want to make sure we interoperate with as many devices as
+ * possible, we will maintain a 240 sector transfer size limit for USB
+ * Mass Storage devices.
+ *
+ * Tests show that other operating have similar limits with Microsoft
+ * Windows 7 limiting transfers to 128 sectors for both USB2 and USB3
+ * and Apple Mac OS X 10.11 limiting transfers to 256 sectors for USB2
+ * and 2048 for USB3 devices.
+ */
+ blk_queue_max_hw_sectors(sdev->request_queue, 240);
}
/*
@@ -626,26 +643,6 @@ static const struct scsi_host_template usb_stor_host_template = {
/* lots of sg segments can be handled */
.sg_tablesize = SG_MAX_SEGMENTS,
-
- /*
- * Limit the total size of a transfer to 120 KB.
- *
- * Some devices are known to choke with anything larger. It seems like
- * the problem stems from the fact that original IDE controllers had
- * only an 8-bit register to hold the number of sectors in one transfer
- * and even those couldn't handle a full 256 sectors.
- *
- * Because we want to make sure we interoperate with as many devices as
- * possible, we will maintain a 240 sector transfer size limit for USB
- * Mass Storage devices.
- *
- * Tests show that other operating have similar limits with Microsoft
- * Windows 7 limiting transfers to 128 sectors for both USB2 and USB3
- * and Apple Mac OS X 10.11 limiting transfers to 256 sectors for USB2
- * and 2048 for USB3 devices.
- */
- .max_sectors = 240,
-
/* emulated HBA */
.emulated = 1,
diff --git a/drivers/usb/storage/uas.c b/drivers/usb/storage/uas.c
index 813c49914b9a..592e1358822e 100644
--- a/drivers/usb/storage/uas.c
+++ b/drivers/usb/storage/uas.c
@@ -843,6 +843,8 @@ static int uas_slave_configure(struct scsi_device *sdev)
blk_queue_max_hw_sectors(sdev->request_queue, 240);
else if (us->pusb_dev->speed >= USB_SPEED_SUPER)
blk_queue_max_hw_sectors(sdev->request_queue, 2048);
+ else
+ blk_queue_max_hw_sectors(sdev->request_queue, SCSI_DEFAULT_MAX_SECTORS);
blk_queue_max_hw_sectors(sdev->request_queue,
min_t(size_t, queue_max_hw_sectors(sdev->request_queue),
--
2.28.0
