Hi Andrew, >> aqc111_read_fw_version(dev, aqc111_data); >> + aqc111_data->autoneg = AUTONEG_ENABLE; >> + aqc111_data->advertised_speed = (usb_speed == USB_SPEED_SUPER) ? >> + SPEED_5000 : SPEED_1000; > > USB 3 has a raw bandwidth of 5Gbps. But it is a shared bus. So you > have no guaranteed you are actually going to get the needed bandwidth > to support line rate. > > USB 2.0 only gives you 480Mbps. So it won't even give you the full > 1G. So using the same reasoning for USB3, maybe you should limit it to > 100Mbps? > > I personally would not apply restrictions on the PHY depending on what > USB is being used. First argument here is to reduce power consumption on USB2. 2.5G/5G uses OCSGMII/XFI serdes which consumes more power. Of course in normal conditions usb2 is capable to feed that, but the risk still exists on legacy usb2 hardware. > This becomes more important when using SFPs. If i have an SFP peer > which is expecting 2500Base-X, but because the device is plugged into > USB 2 port it is forced to use 1000Base-X, it is not going to get > link. Do you mean here 2500Base-T? This particular device is an integrated mac+phy, thus we can't easily link it with -X SFP endpoint. Although its not a common usecase for the consumer dongle to connect to SFP endpoints, think your comment is quite reasonable. We'll clarify this internally. Regards, Igor
