From: Lorenzo Colitti <lorenzo@google.com>
Date: Tue, 18 Aug 2020 16:19:49 +0000 (+0900)
Subject: usb: gadget: u_ether: enable qmult on SuperSpeed Plus as well
X-Git-Tag: v4.9.241~89
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=d09f63a3a7b641f96fe30aefbb2b724cede72207;p=platform%2Fkernel%2Flinux-amlogic.git

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@google.com>
Signed-off-by: Lorenzo Colitti <lorenzo@google.com>
Signed-off-by: Felipe Balbi <balbi@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

diff --git a/drivers/usb/gadget/function/u_ether.c b/drivers/usb/gadget/function/u_ether.c
index d5fbc2352029..589d1f5fb575 100644
--- a/drivers/usb/gadget/function/u_ether.c
+++ b/drivers/usb/gadget/function/u_ether.c
@@ -97,7 +97,7 @@ 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;