On Tue. 20 Feb. 2024 at 17:10, Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx> wrote: > > On 20.02.2024 08:49:26, Dr. Michael 'Mickey' Lauer wrote: > > Hi Marc, > > > > >> > > >> Sounds pretty cool. Our design is based on an ESP32-S3 though, so I > > >> have to duplicate that effort. Is there some kind of USB protocol > > >> definition for what gs-usb expects or do I need to learn that from the > > >> implementation? > > > > > > I've put together a very rough summary of the driver's side of view: > > > > > > https://gist.github.com/marckleinebudde/99f72d9db67accf08cc6efa367cfe54b > > > > > > Feel free to update. > > > > Wow, that’s very kind of you! > > :) > > > Later this year I’ll take this blueprint to implement the necessary > > changes in our firmware. I’ll enhance / update your summary > > as I’ll go. > > If you discover any odd points or areas for improvement in the USB > protocol, please let us know. > > Currently, TX-complete sends the _entire_ structure back to the host, > which is quite an overhead, especially for CAN FD frames. We're working > on a "short-tx-complete" feature. The es581.4 may be doing what you are looking for: - When sending a frame, the driver attaches a 32 bit index: https://elixir.bootlin.com/linux/v6.7/source/drivers/net/can/usb/etas_es58x/es581_4.h#L78 - When receiving the TX completion message, the device just send back that index and a timestamp: https://elixir.bootlin.com/linux/v6.7/source/drivers/net/can/usb/etas_es58x/es581_4.h#L97 The device is agnostic of what this index represents. The driver uses the index from the can_put_echo_skb() / can_get_echo_skb(). (in addition the driver can handle bulk send and receive but that's another story). Yours sincerely, Vincent Mailhol
