Re: [PATCH v3 1/1] can: dev: add software tx timestamps

[Richard Cochran]

On Sun, Jan 10, 2021 at 09:49:03PM +0900, Vincent Mailhol wrote:
>   * The hardware rx timestamp of a local loopback message is the
>     hardware tx timestamp. This means that there are no needs to
>     implement SOF_TIMESTAMPING_TX_HARDWARE for CAN sockets.

I can't agree with that statement.  The local loopback is a special
"feature" of CAN sockets, and some programs turn it off.  Furthermore,
requiring user space to handle CAN sockets differently WRT Tx time
stamps is user-unfriendly.  So I would strongly support adding
SOF_TIMESTAMPING_TX_HARDWARE to the CAN layer in the future.

(This isn't a criticism of the current patch, though.)

Thanks,
Richard