From: Vincent Mailhol <mailhol.vincent@xxxxxxxxxx> When the FD is turned off through the netlink interface, the data bit timing values still remain in data_bittiming and are displayed despite of the feature being disabled. Example: | $ ip link set can0 type can bitrate 500000 dbitrate 2000000 fd on | $ ip --details link show can0 | 1: can0: <NOARP,ECHO> mtu 72 qdisc pfifo_fast state DOWN mode DEFAULT group default qlen 10 | link/can promiscuity 0 minmtu 0 maxmtu 0 | can <FD> state STOPPED restart-ms 0 | bitrate 500000 sample-point 0.875 | tq 12 prop-seg 69 phase-seg1 70 phase-seg2 20 sjw 1 | ES582.1/ES584.1: tseg1 2..256 tseg2 2..128 sjw 1..128 brp 1..512 brp-inc 1 | dbitrate 2000000 dsample-point 0.750 | dtq 12 dprop-seg 14 dphase-seg1 15 dphase-seg2 10 dsjw 1 | ES582.1/ES584.1: dtseg1 2..32 dtseg2 1..16 dsjw 1..8 dbrp 1..32 dbrp-inc 1 | clock 80000000 numtxqueues 1 numrxqueues 1 gso_max_size 65536 gso_max_segs 65535 | | $ ip link set can0 type can bitrate 500000 fd off | $ ip --details link show can0 | 1: can0: <NOARP,ECHO> mtu 16 qdisc pfifo_fast state DOWN mode DEFAULT group default qlen 10 | link/can promiscuity 0 minmtu 0 maxmtu 0 | can state STOPPED restart-ms 0 | bitrate 500000 sample-point 0.875 | tq 12 prop-seg 69 phase-seg1 70 phase-seg2 20 sjw 1 | ES582.1/ES584.1: tseg1 2..256 tseg2 2..128 sjw 1..128 brp 1..512 brp-inc 1 | dbitrate 2000000 dsample-point 0.750 | dtq 12 dprop-seg 14 dphase-seg1 15 dphase-seg2 10 dsjw 1 | ES582.1/ES584.1: dtseg1 2..32 dtseg2 1..16 dsjw 1..8 dbrp 1..32 dbrp-inc 1 | clock 80000000 numtxqueues 1 numrxqueues 1 gso_max_size 65536 gso_max_segs 65535 Remark: once FD is turned off, it is not possible to turn fd back on and reuse the previously input data bit timing values: | $ ip link set can0 type can bitrate 500000 fd on | RTNETLINK answers: Operation not supported This means that the user will need to re-configure the data bit timing in order to turn fd on again. Because old data bit timing values cannot be reused, this patch clears priv->data_bit timing whenever FD is turned off. This way, the data bit timing variables are not displayed anymore. Link: https://lore.kernel.org/r/20210618081904.141114-2-mailhol.vincent@xxxxxxxxxx Signed-off-by: Vincent Mailhol <mailhol.vincent@xxxxxxxxxx> Signed-off-by: Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx> --- drivers/net/can/dev/netlink.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/drivers/net/can/dev/netlink.c b/drivers/net/can/dev/netlink.c index e38c2566aff4..b567fd628c17 100644 --- a/drivers/net/can/dev/netlink.c +++ b/drivers/net/can/dev/netlink.c @@ -132,10 +132,13 @@ static int can_changelink(struct net_device *dev, struct nlattr *tb[], priv->ctrlmode |= maskedflags; /* CAN_CTRLMODE_FD can only be set when driver supports FD */ - if (priv->ctrlmode & CAN_CTRLMODE_FD) + if (priv->ctrlmode & CAN_CTRLMODE_FD) { dev->mtu = CANFD_MTU; - else + } else { dev->mtu = CAN_MTU; + memset(&priv->data_bittiming, 0, + sizeof(priv->data_bittiming)); + } } if (data[IFLA_CAN_RESTART_MS]) { -- 2.30.2
