Thanks for your review.

On 01/31/2022 3:08 AM Vincent MAILHOL [off-list ref] wrote:

quoted

@@ -1435,13 +1488,15 @@ static netdev_tx_t rcar_canfd_start_xmit(struct sk_buff *skb,

        dlc = RCANFD_CFPTR_CFDLC(can_fd_len2dlc(cf->len));

-       if (priv->can.ctrlmode & CAN_CTRLMODE_FD) {
+       if ((priv->can.ctrlmode & CAN_CTRLMODE_FD) ||
+           gpriv->chip_id == RENESAS_R8A779A0) {
                rcar_canfd_write(priv->base,
                                 RCANFD_F_CFID(ch, RCANFD_CFFIFO_IDX), id);
                rcar_canfd_write(priv->base,
                                 RCANFD_F_CFPTR(ch, RCANFD_CFFIFO_IDX), dlc);

-               if (can_is_canfd_skb(skb)) {
+               if ((priv->can.ctrlmode & CAN_CTRLMODE_FD) &&
+                   can_is_canfd_skb(skb)) {

Could you explain why this additional check is needed?
My understanding is that can_is_canfd_skb(skb) being true implies
that the CAN_CTRLMODE_FD flag is set.

That might indeed be redundant.

quoted

                        /* CAN FD frame format */
                        sts |= RCANFD_CFFDCSTS_CFFDF;
                        if (cf->flags & CANFD_BRS)

@@ -1488,22 +1543,29 @@ static netdev_tx_t rcar_canfd_start_xmit(struct sk_buff *skb,
 static void rcar_canfd_rx_pkt(struct rcar_canfd_channel *priv)
 {
        struct net_device_stats *stats = &priv->ndev->stats;
+       struct rcar_canfd_global *gpriv = priv->gpriv;
        struct canfd_frame *cf;
        struct sk_buff *skb;
        u32 sts = 0, id, dlc;
        u32 ch = priv->channel;
        u32 ridx = ch + RCANFD_RFFIFO_IDX;

-       if (priv->can.ctrlmode & CAN_CTRLMODE_FD) {
+       if ((priv->can.ctrlmode & CAN_CTRLMODE_FD) ||
+           gpriv->chip_id == RENESAS_R8A779A0) {

I guess that this is linked to the above comment. Does the
R8A779A0 chip support CAN-FD? If yes, why not simply use the
CAN_CTRLMODE_FD instead of adding this additional check?

The non-V3U Gen3 CAN controllers have two different ways to be driven, depending on whether they are in classic or CAN-FD mode. The V3U controller is driven the CAN-FD way in both modes and thus needs to have this branch taken no matter what mode it is in.

CU
Uli