On Tue, 13 Mar 2018 17:27:21 +0200 Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx> wrote: > Example for clarification: > Gen 1x1 = 5Gbps, SuperSpeed, one lane, same as USB3.0, and USB 3.1 Gen1 > Gen 2x1 = 10Gbps, SuperSpeedPlus, one lane, same as USB 3.1 Gen2 > Gen 1x2 = 10Gbps, SuperSpeed, Dual-lane (2 x 5Gbps) > Gen 2x2 = 20Gbps, SuperSpeedPlus, Dual-lane (2 x 10Gbps) > > > 4. Should the "speed" sysfs entry be more accurate? USB 3.1 and later > can list different supported lane speeds other than the 5Gbps or 10Gbps. > actual port speed would be lane count * current lane speed in use. > Or do we just keep it simple and show the maximum signaling > rate * lane count, i.e. 5000, 10000 or 20000? > and show "SSIC" instead of "Gen XxY" for asymetric lane SSIC devices, > skipping details on rx and tx lane counts. > Please do not compute "signaling rate * count", because it is very misleading and that value cannot be used to verify whether the hardware works at its maximum available speed or not. Gen 1x2 is not 5 * 2 = 10 Gbps, but only 8 Gbps (like Gb Ethernet is 1 Gbps, not 1.25 Gbps), while Gen 2x1 is very close to 10 Gbps, i.e. significantly faster (due to a different encoding), so it would be wrong to display them as equivalent. Best regards! -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
