From: Lorenzo Colitti <lore...@google.com>
[ 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 <m...@google.com>
Signed-off-by: Lorenzo Colitti <lore...@google.com>
Signed-off-by: Felipe Balbi <ba...@kernel.org>
Signed-off-by: Sasha Levin <sas...@kernel.org>
---
drivers/usb/gadget/function/u_ether.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/usb/gadget/function/u_ether.c
b/drivers/usb/gadget/function/u_ether.c
index e69f20b2a3f44..46c50135ef9f7 100644
--- a/drivers/usb/gadget/function/u_ether.c
+++ b/drivers/usb/gadget/function/u_ether.c
@@ -96,7 +96,7 @@ 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;
--
2.25.1
