[PATCH 3.16 007/125] uas: Limit qdepth to 32 when connected over usb-2

Greg Kroah-Hartman
2014-09-03T23:14:08Z

From: Hans de Goede <hdegoede@redhat.com>

commit e2875c33787ebda21aeecc1a9d3ff52b3aa413ec upstream.

Some jmicron uas chipsets act up (they disconnect from the bus) when sending
more then 32 commands to them at once.

Rather then building an ever growing list with usb-id based quirks for
devices using this chipset, simply reduce the qdepth to 32 when connected
over usb-2. 32 should be plenty to keep things close to maximum
possible throughput on usb-2.

Tested-and-reported-by: Laszlo T. <tlacix@gmail.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/usb/storage/uas.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/usb/storage/uas.c
+++ b/drivers/usb/storage/uas.c
@@ -1026,7 +1026,7 @@ static int uas_configure_endpoints(struc
usb_endpoint_num(&eps[3]->desc));

if (udev->speed != USB_SPEED_SUPER) {
- devinfo->qdepth = 256;
+ devinfo->qdepth = 32;
devinfo->use_streams = 0;
} else {
devinfo->qdepth = usb_alloc_streams(devinfo->intf, eps + 1,