usb: gadget: f_ncm: set SuperSpeed bulk descriptor bMaxBurst to 15

This improves performance on fast connections. When directly
connecting to a Linux laptop running 5.6, single-stream iperf3
goes from ~1.7Gbps to ~2.3Gbps out, and from ~620Mbps to ~720Mbps
in.

Reviewed-by: Maciej Żenczykowski <maze@google.com>
Signed-off-by: Lorenzo Colitti <lorenzo@google.com>
Signed-off-by: Felipe Balbi <balbi@kernel.org>

diff --git a/drivers/usb/gadget/function/f_ncm.c b/drivers/usb/gadget/function/f_ncm.c
index 7672fa2..ffa397a 100644 (file)
--- a/drivers/usb/gadget/function/f_ncm.c
+++ b/drivers/usb/gadget/function/f_ncm.c
@@ -378,7 +378,7 @@ static struct usb_ss_ep_comp_descriptor ss_ncm_bulk_comp_desc = {
        .bDescriptorType =      USB_DT_SS_ENDPOINT_COMP,
 
        /* the following 2 values can be tweaked if necessary */
-       /* .bMaxBurst =         0, */
+       .bMaxBurst =            15,
        /* .bmAttributes =      0, */
 };