Hello Joakim, I successfully validated your CAN FD support on an S32V234 based board. Here are some points which are not very clear to me: Joakim Zhang <qiangqing.zhang@xxxxxxx> writes: > + priv->write(reg_mcr | FLEXCAN_MCR_FDEN, ®s->mcr); According to the S32V234 reference manual (not sure if this applies to i.MX8QM as well), CAN_CTRL1[SMP] cannot be asserted when CAN FD is enabled. Is it safe to configure the interface with both "fd on" and "triple-sampling on"? If not, flexcan_open should return an error when both CAN_CTRLMODE_FD and CAN_CTRLMODE_3_SAMPLES are set in ctrlmode. Joakim Zhang <qiangqing.zhang@xxxxxxx> writes: > + priv->offload.is_canfd = true; Shouldn't is_canfd be assigned false in the "else" branch? Otherwise, is_canfd will stay true after the following sequence: root@s32v234evb:~# ip link set can0 type can bitrate 500000 dbitrate 2000000 fd on root@s32v234evb:~# ip link set can0 up root@s32v234evb:~# ip link set can0 down root@s32v234evb:~# ip link set can0 type can bitrate 500000 fd off root@s32v234evb:~# ip link set can0 up Moreover, I wonder if we even need is_canfd, because frames should be fed to the kernel as classic or FD based only on the EDL bit in the C/S word of the Rx MB, to keep their original format. That is, you may either read EDL from within a new callback (but I think that mailbox_read should remain the only one which both locks and unlocks the mailboxes) or let mailbox_read call alloc_can(fd)_skb itself. Regards, Stefan
