On 14.03.2018 12:29, Oliver Neukum wrote:
Am Dienstag, den 13.03.2018, 19:22 +0200 schrieb Mathias Nyman:
My understanding is that Gen XxY notion is only used for symmetric devices
where tx lanes = rx lanes. Only SSIC devices can be asymmetric.
USB 3.2 spec mentions the (Gen 1x1, 1x2, 2x1 and 2x2) alternatives, nothing more.
Nothing about different lane counts on rx and tx related to Gen XxY.
Hi,
normally I would say that we should worry about this only when we need
to, but an API in sysfs is an exception to that rule. We can avoid
pain later if we export lane counts for both directions now
in all cases.
Sounds reasonable, I'll add both rx_lanes and tx_lanes
We should also export all raw data we have. User space can be trusted
to get a multiplication right and it is not the kernels job
to interpret such data.
Do I understand correctly that you propose the "speed" sysfs entry
should only show the lane signaling rate, i.e. 5000 or 10000 for USB 3.x.
Adding rx_lanes and tx_lanes and keeping "speed" as lane signaling rate
is probably the cleanest and most straight forward approach.
I still would like to add a "Gen XxY" or "SSIC" to the
"new/reset SuperSpeed USB device number using " dev_info string.
It's a quick way of checking if the device works at the expected speed when
connecting a device.
An thoughts about that?
-Mathias
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