From: Lorenzo Colitti lorenzo@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 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 --- 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 c3cc6bd14e615..31ea76adcc0db 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;