On 23.07.25 03:29, yicongsrfy@163.com wrote:

No, the standard does not mention anything about duplex at all.

However, Chapter 2 of the standard describes the scope of devices
covered by CDC, including wired and wireless network adapters,
among others.

We know that wireless communication is inherently half-duplex;

Well, no. 802.11 is half-duplex. Cell phones are capable of full
duplex. CDC is not just network cards.

for wired network adapters, the duplex status depends on the
capabilities of both communication ends.

On ethernet. Again CDC is not limited to ethernet.
  

 From these two tests, we can conclude that both full-duplex
and half-duplex modes are supported — the problem is simply
that the duplex status cannot be retrieved in the absence of
MII support.

Sort of. You are asking a generic driver to apply a concept
from ethernet. It cannot. Ethernet even if it is half-duplex
is very much symmetrical in speed. Cable modems do not, just
to give an example.

I think we need to centralize the reaction to stuff that is not ethernet.

	Regards
		Oliver