On 07/31/2018 09:38 AM, Pankaj Bansal wrote: > >> -----Original Message----- >> From: Marc Kleine-Budde [mailto:mkl@xxxxxxxxxxxxxx] >> Sent: Tuesday, July 31, 2018 12:44 PM >> To: Pankaj Bansal <pankaj.bansal@xxxxxxx>; linux-can@xxxxxxxxxxxxxxx >> Subject: Re: [PATCH 6/6] net: can: flexcan: use CAN FD frames for Tx/Rx >> >> On 07/31/2018 08:00 AM, Pankaj Bansal wrote: >>>> -----Original Message----- >>>> From: Marc Kleine-Budde [mailto:mkl@xxxxxxxxxxxxxx] >>>> Sent: Monday, July 30, 2018 8:16 PM >>>> To: Pankaj Bansal <pankaj.bansal@xxxxxxx>; linux-can@xxxxxxxxxxxxxxx >>>> Subject: Re: [PATCH 6/6] net: can: flexcan: use CAN FD frames for >>>> Tx/Rx >>>> >>>> On 07/30/2018 06:07 PM, Pankaj Bansal wrote: >>>>> Use can FD frames for Tx/Rx operations. This would be needed in >>>>> upcoming SOC LX2160A, which supports CAN FD protocol >>>> >>>> Have you tested this with a CAN-2.0 compatible controller? Does the >>>> userspace still work as expected if you pass CAN_RAW a CAN-FD frames >>>> which only carries CAN-2.0? See >>>> https://elixir.bootlin.com/linux/latest/source/net/can/raw.c#L811 >>> >>> I have tested this using cangen command to generate CAN 2.0 frames, in >> LS1021A-TWR board. >> >> Yes.... >> >>> # ip link set can0 up type can bitrate 125000 [ 103.699095] IPv6: >>> ADDRCONF(NETDEV_CHANGE): can0: link becomes ready # ip link set >> can1 >>> up type can bitrate 125000 [ 107.832078] IPv6: >>> ADDRCONF(NETDEV_CHANGE): can1: link becomes ready # candump can0 >> & # >>> candump can1 & >> >> ... but candump will switch the socket into CAN-FD mode. Your code will >> however break existing userspace applications that do not switch on CAN- >> FD mode. Maybe we should add a cmd-line parameter to candump do >> disable CAN-FD mode. > > There is an option in ip command to turn the FD mode on. > -> ip link set can0 up type can bitrate 125000 dbitrate 250000 fd on > > I thought this command configures the CAN interface in FD mode. And normal command > -> ip link set can0 up type can bitrate 125000 > configures CAN interface In CAN 2.0 mode. Yes - If your driver supports this "ip" command. But your patches switch the driver into CAN-FD mode unconditionally. > Is there any test steps that I can follow to test if these changes > will break existing applications or not? Yes - don't let candump switch on CAN-FD mode: -------->8-------->8-------->8-------->8-------->8-------->8-------->8-------->8-------->8-------- diff --git a/candump.c b/candump.c index f98d1c3d378c..331320a7a696 100644 --- a/candump.c +++ b/candump.c @@ -535,8 +535,10 @@ int main(int argc, char **argv) } /* if (nptr) */ +#if 0 /* try to switch the socket into CAN FD mode */ setsockopt(s[i], SOL_CAN_RAW, CAN_RAW_FD_FRAMES, &canfd_on, sizeof(canfd_on)); +#endif if (rcvbuf_size) { -------->8-------->8-------->8-------->8-------->8-------->8-------->8-------->8-------->8-------- Marc -- Pengutronix e.K. | Marc Kleine-Budde | Industrial Linux Solutions | Phone: +49-231-2826-924 | Vertretung West/Dortmund | Fax: +49-5121-206917-5555 | Amtsgericht Hildesheim, HRA 2686 | http://www.pengutronix.de |
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