On 12/14/20 10:14 AM, Marc Kleine-Budde wrote: > From: Vincent Mailhol <mailhol.vincent@xxxxxxxxxx> > > This patch adds the function can_skb_get_dll_len() which returns the length of > a CAN frame on the data link layer, including Start-of-frame, Identifier, > various other bits, the CRC, the End-of-frame, the Inter frame spacing and the > actual data. > > Co-developed-by: Arunachalam Santhanam <arunachalam.santhanam@xxxxxxxxxxxx> > Not-Signed-off-by: Arunachalam Santhanam <arunachalam.santhanam@xxxxxxxxxxxx> > Co-developed-by: Vincent Mailhol <mailhol.vincent@xxxxxxxxxx> > Not-Signed-off-by: Vincent Mailhol <mailhol.vincent@xxxxxxxxxx> > Co-developed-by: Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx> > Signed-off-by: Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx> > --- > Hello, > > while reviewing the etas_es58X driver and hacking on BQL support for the > mcp251xfd driver, it turned out the a function to calculate the length of the > CAN frame that's send over the wire should go into the generic CAN dev code. > > Looking at the CAN and OSI layering I think the first layer where we have all > the bits that we see on the wire is the data link layer (DLL). > > https://www.can-cia.org/can-knowledge/can/can-data-link-layers > > This is why I named the function can_skb_get_dll_len(). > > I'm planing to add a (better) calculation of the CAN-FD dll_len, depending on > the data and including different CRC lengths. > > As this code is copied from the etas_es58X driver, I've added the authors as > Co-developed-by and I'd like to add their S-o-b to this patch. > > Please review and commnt on the naming on the functions. When implementing BQL we need the CAN frame's DLL len twice: 1. When sending the package to the hardware 2. After the TX-complete IRQ We can calculate this information twice, but I thought we might put it into the struct can_skb_priv. https://elixir.bootlin.com/linux/latest/source/include/linux/can/skb.h#L34 Thoughts? regards, Marc -- Pengutronix e.K. | Marc Kleine-Budde | Embedded Linux | https://www.pengutronix.de | Vertretung West/Dortmund | Phone: +49-231-2826-924 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
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