[ Upstream commit 530e0d46c61314c59ecfdb8d3bcb87edbc0f85d3 ]
The N_As value describes the time a CAN frame needs on the wire when
transmitted by the CAN controller. Even very short CAN FD frames need
arround 100 usecs (bitrate 1Mbit/s, data bitrate 8Mbit/s).
Having N_As to be zero (the former default) leads to 'no CAN frame
separation' when STmin is set to zero by the receiving node. This 'burst
mode' should not be enabled by default as it could potentially dump a high
number of CAN frames into the netdev queue from the soft hrtimer context.
This does not affect the system stability but is just not nice and
cooperative.
With this N_As/frame_txtime value the 'burst mode' is disabled by default.
As user space applications usually do not set the frame_txtime element
of struct can_isotp_options the new in-kernel default is very likely
overwritten with zero when the sockopt() CAN_ISOTP_OPTS is invoked.
To make sure that a N_As value of zero is only set intentional the
value '0' is now interpreted as 'do not change the current value'.
When a frame_txtime of zero is required for testing purposes this
CAN_ISOTP_FRAME_TXTIME_ZERO u32 value has to be set in frame_txtime.
Link: https://lore.kernel.org/all/20220309120416.83514-2-socketcan@hartkopp.net
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit 921ca574cd382142add8b12d0a7117f495510de5 upstream.
When CAN_ISOTP_SF_BROADCAST is set in the CAN_ISOTP_OPTS flags the CAN_ISOTP
socket is switched into functional addressing mode, where only single frame
(SF) protocol data units can be send on the specified CAN interface and the
given tp.tx_id after bind().
In opposite to normal and extended addressing this socket does not register a
CAN-ID for reception which would be needed for a 1-to-1 ISOTP connection with a
segmented bi-directional data transfer.
Sending SFs on this socket is therefore a TX-only 'broadcast' operation.
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: Thomas Wagner <thwa1@web.de>
Link: https://lore.kernel.org/r/20201206144731.4609-1-socketcan@hartkopp.net
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
CAN Transport Protocols offer support for segmented Point-to-Point
communication between CAN nodes via two defined CAN Identifiers.
As CAN frames can only transport a small amount of data bytes
(max. 8 bytes for 'classic' CAN and max. 64 bytes for CAN FD) this
segmentation is needed to transport longer PDUs as needed e.g. for
vehicle diagnosis (UDS, ISO 14229) or IP-over-CAN traffic.
This protocol driver implements data transfers according to
ISO 15765-2:2016 for 'classic' CAN and CAN FD frame types.
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
Link: https://lore.kernel.org/r/20200928200404.82229-1-socketcan@hartkopp.net
[mkl: Removed "WITH Linux-syscall-note" from isotp.c.
Fixed indention, a checkpatch warning and typos.
Replaced __u{8,32} by u{8,32}.
Removed always false (optlen < 0) check in isotp_setsockopt().]
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
