From: Lorenzo Colitti lorenzo@google.com
[ Upstream commit 986499b1569af980a819817f17238015b27793f6 ]
Currently, SuperSpeed NCM gadgets report a speed of 851 Mbps in USB_CDC_NOTIFY_SPEED_CHANGE. But the calculation appears to assume 16 packets per microframe, and USB 3 and above no longer use microframes.
Maximum speed is actually much higher. On a direct connection, theoretical throughput is at most 3.86 Gbps for gen1x1 and 9.36 Gbps for gen2x1, and I have seen gadget->host iperf throughput of >2 Gbps for gen1x1 and >4 Gbps for gen2x1.
Unfortunately the ConnectionSpeedChange defined in the CDC spec only uses 32-bit values, so we can't report accurate numbers for 10Gbps and above. So, report 3.75Gbps for SuperSpeed (which is roughly maximum theoretical performance) and 4.25Gbps for SuperSpeed Plus (which is close to the maximum that we can report in a 32-bit unsigned integer).
This results in:
[50879.191272] cdc_ncm 2-2:1.0 enx228b127e050c: renamed from usb0 [50879.234778] cdc_ncm 2-2:1.0 enx228b127e050c: 3750 mbit/s downlink 3750 mbit/s uplink
on SuperSpeed and:
[50798.434527] cdc_ncm 8-2:1.0 enx228b127e050c: renamed from usb0 [50798.524278] cdc_ncm 8-2:1.0 enx228b127e050c: 4250 mbit/s downlink 4250 mbit/s uplink
on SuperSpeed Plus.
Fixes: 1650113888fe ("usb: gadget: f_ncm: add SuperSpeed descriptors for CDC NCM") 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/f_ncm.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/usb/gadget/function/f_ncm.c b/drivers/usb/gadget/function/f_ncm.c index e2eefdd8bf78..09bc917d407d 100644 --- a/drivers/usb/gadget/function/f_ncm.c +++ b/drivers/usb/gadget/function/f_ncm.c @@ -86,8 +86,10 @@ static inline struct f_ncm *func_to_ncm(struct usb_function *f) /* peak (theoretical) bulk transfer rate in bits-per-second */ static inline unsigned ncm_bitrate(struct usb_gadget *g) { - if (gadget_is_superspeed(g) && g->speed == USB_SPEED_SUPER) - return 13 * 1024 * 8 * 1000 * 8; + if (gadget_is_superspeed(g) && g->speed >= USB_SPEED_SUPER_PLUS) + return 4250000000U; + else if (gadget_is_superspeed(g) && g->speed == USB_SPEED_SUPER) + return 3750000000U; else if (gadget_is_dualspeed(g) && g->speed == USB_SPEED_HIGH) return 13 * 512 * 8 * 1000 * 8; else