This is a note to let you know that I've just added the patch titled
usb: gadget: u_ether: enable qmult on SuperSpeed Plus as well
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
usb-gadget-u_ether-enable-qmult-on-superspeed-plus-a.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 31e2324c58b6e3d798d22ed0664bc77dfc6f69fe
Author: Lorenzo Colitti <lorenzo@xxxxxxxxxx>
Date: Wed Aug 19 01:19:49 2020 +0900
usb: gadget: u_ether: enable qmult on SuperSpeed Plus as well
[ Upstream commit 4eea21dc67b0c6ba15ae41b1defa113a680a858e ]
The u_ether driver has a qmult setting that multiplies the
transmit queue length (which by default is 2).
The intent is that it should be enabled at high/super speed, but
because the code does not explicitly check for USB_SUPER_PLUS,
it is disabled at that speed.
Fix this by ensuring that the queue multiplier is enabled for any
wired link at high speed or above. Using >= for USB_SPEED_*
constants seems correct because it is what the gadget_is_xxxspeed
functions do.
The queue multiplier substantially helps performance at higher
speeds. On a direct SuperSpeed Plus link to a Linux laptop,
iperf3 single TCP stream:
Before (qmult=1): 1.3 Gbps
After (qmult=5): 3.2 Gbps
Fixes: 04617db7aa68 ("usb: gadget: add SS descriptors to Ethernet gadget")
Reviewed-by: Maciej Żenczykowski <maze@xxxxxxxxxx>
Signed-off-by: Lorenzo Colitti <lorenzo@xxxxxxxxxx>
Signed-off-by: Felipe Balbi <balbi@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/usb/gadget/function/u_ether.c b/drivers/usb/gadget/function/u_ether.c
index fbe96ef1ac7a4..891e9f7f40d59 100644
--- a/drivers/usb/gadget/function/u_ether.c
+++ b/drivers/usb/gadget/function/u_ether.c
@@ -93,7 +93,7 @@ struct eth_dev {
static inline int qlen(struct usb_gadget *gadget, unsigned qmult)
{
if (gadget_is_dualspeed(gadget) && (gadget->speed == USB_SPEED_HIGH ||
- gadget->speed == USB_SPEED_SUPER))
+ gadget->speed >= USB_SPEED_SUPER))
return qmult * DEFAULT_QLEN;
else
return DEFAULT_QLEN;
