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usb: gadget: u_ether: enable qmult on SuperSpeed Plus as well

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[ Upstream commit 4eea21dc67 ]

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: 04617db7aa ("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>
This commit is contained in:
Lorenzo Colitti
2020-08-19 01:19:49 +09:00
committed by Greg Kroah-Hartman
parent c7436c5d5e
commit c870551d3d
1 changed files with 1 additions and 1 deletions
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2
drivers/usb/gadget/function/u_ether.c
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@@ -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;