On Tue. 4 Mai 2021 at 21:22, Vincent MAILHOL <mailhol.vincent@xxxxxxxxxx> wrote: > On Mar. 4 Mai 2021 at 16:48, Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx> wrote: > > On 04.05.2021 06:46:17, Vincent MAILHOL wrote: [...] > > > Are you still able to send frames and receive the echo if there is a > > > single node on the network? > > > > No - But the peak driver/hw has some limitations: > > > > The peak driver doesn't have TX complete signaling, it send the echo > > after sending the TX CAN frame via USB. And the peak controller seems to > > buffer quite a lot TX CAN frames, so it looks for the first ~72 frames > > like the bus is still working. > > Yes, I also noticed that when I had peak devices in my test > lab. The peak driver call can_put_echo_skb() inside > peak_usb_ndo_start_xmit() and thus, the echo frames do not > reflect whether the actual completion occured or not. I guess > fixing that should not be too hard but I do not have access to > that hardware anymore to do it myself. > > I am just surprised by the value of 72 frames. My understanding > is that peak_usb_ndo_start_xmit() should stop the network queue > whenever the number of active tx urbs reaches 10. > Ref: > https://elixir.bootlin.com/linux/latest/source/drivers/net/can/usb/peak_usb/pcan_usb_core.c#L399 > https://elixir.bootlin.com/linux/latest/source/drivers/net/can/usb/peak_usb/pcan_usb_core.h#L29 Hi Marc, please ignore above paragraphs. I mixed up the tx buffer with the TX frame buffer. Also, implementing a full TX completion might actually not be possible due to the Peak device limitations.
