The CAN FD data bittiming constants are provided via netlink only when there 
are valid CAN FD constants available in priv->data_bittiming_const. 

Due to the indirection of pointer assignments in the peak_usb driver the 
priv->data_bittiming_const never becomes NULL - not even for non-FD adapters. 

The data_bittiming_const points to zero'ed data which leads to this result 
when running 'ip -details link show can0': 

35: can0: <NOARP,ECHO> mtu 16 qdisc noop state DOWN mode DEFAULT group default qlen 10 
    link/can  promiscuity 0 
    can state STOPPED restart-ms 0 
  pcan_usb: tseg1 1..16 tseg2 1..8 sjw 1..4 brp 1..64 brp-inc 1 
  : dtseg1 0..0 dtseg2 0..0 dsjw 1..0 dbrp 0..0 dbrp-inc 0  <== BROKEN! 
  clock 8000000 

This patch sets the dev_set_data_bittiming in struct peak_adapter to NULL to 
be able to disable the CAN FD specific information on non-FD adapters. 

Relevant for stable kernels 4.0+ 

Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net> 
--- 
drivers/net/can/usb/peak_usb/pcan_usb.c      | 1 + 
drivers/net/can/usb/peak_usb/pcan_usb_core.c | 9 +++++++-- 
drivers/net/can/usb/peak_usb/pcan_usb_pro.c  | 1 + 
3 files changed, 9 insertions(+), 2 deletions(-) 

diff --git a/drivers/net/can/usb/peak_usb/pcan_usb.c b/drivers/net/can/usb/peak_usb/pcan_usb.c 
index 6b94007..5c4b270 100644 
--- a/drivers/net/can/usb/peak_usb/pcan_usb.c 
+++ b/drivers/net/can/usb/peak_usb/pcan_usb.c 

@@ -896,6 +896,7 @@ const struct peak_usb_adapter pcan_usb = { 

.dev_init = pcan_usb_init, 
.dev_set_bus = pcan_usb_write_mode, 
.dev_set_bittiming = pcan_usb_set_bittiming, 
+ .dev_set_data_bittiming = NULL, 
.dev_get_device_id = pcan_usb_get_device_id, 
.dev_decode_buf = pcan_usb_decode_buf, 
.dev_encode_msg = pcan_usb_encode_msg, 

diff --git a/drivers/net/can/usb/peak_usb/pcan_usb_core.c b/drivers/net/can/usb/peak_usb/pcan_usb_core.c 
index 7921cff..76c0624 100644 
--- a/drivers/net/can/usb/peak_usb/pcan_usb_core.c 
+++ b/drivers/net/can/usb/peak_usb/pcan_usb_core.c 

@@ -794,8 +794,13 @@ static int peak_usb_create_dev(const struct peak_usb_adapter *peak_usb_adapter, 

dev->can.clock = peak_usb_adapter->clock; 
dev->can.bittiming_const = &peak_usb_adapter->bittiming_const; 
dev->can.do_set_bittiming = peak_usb_set_bittiming; 
- dev->can.data_bittiming_const = &peak_usb_adapter->data_bittiming_const; 
- dev->can.do_set_data_bittiming = peak_usb_set_data_bittiming; 
+ if (peak_usb_adapter->dev_set_data_bittiming) { 
+ dev->can.data_bittiming_const = &peak_usb_adapter->data_bittiming_const; 
+ dev->can.do_set_data_bittiming = peak_usb_set_data_bittiming; 
+ } else { 
+ dev->can.data_bittiming_const = NULL; 
+ dev->can.do_set_data_bittiming = NULL; 
+ } 
dev->can.do_set_mode = peak_usb_set_mode; 
dev->can.do_get_berr_counter = peak_usb_adapter->do_get_berr_counter; 
dev->can.ctrlmode_supported = peak_usb_adapter->ctrlmode_supported; 

diff --git a/drivers/net/can/usb/peak_usb/pcan_usb_pro.c b/drivers/net/can/usb/peak_usb/pcan_usb_pro.c 
index 7d61b32..9111a54 100644 
--- a/drivers/net/can/usb/peak_usb/pcan_usb_pro.c 
+++ b/drivers/net/can/usb/peak_usb/pcan_usb_pro.c 

@@ -1048,6 +1048,7 @@ const struct peak_usb_adapter pcan_usb_pro = { 

.dev_free = pcan_usb_pro_free, 
.dev_set_bus = pcan_usb_pro_set_bus, 
.dev_set_bittiming = pcan_usb_pro_set_bittiming, 
+ .dev_set_data_bittiming = NULL, 
.dev_get_device_id = pcan_usb_pro_get_device_id, 
.dev_decode_buf = pcan_usb_pro_decode_buf, 
.dev_encode_msg = pcan_usb_pro_encode_msg, 
-- 
2.1.4