The actual payload length of the CAN Remote Transmission Request (RTR)
frames is always 0, i.e. no payload is transmitted on the wire.
However, those RTR frames still use the DLC to indicate the length of
the requested frame.
As such, net_device_stats::tx_bytes should not be increased when
sending RTR frames.
The function can_get_echo_skb() already returns the correct length,
even for RTR frames (c.f. [1]). However, for historical reasons, the
drivers do not use can_get_echo_skb()'s return value and instead, most
of them store a temporary length (or dlc) in some local structure or
array. Using the return value of can_get_echo_skb() solves the
issue. After doing this, such length/dlc fields become unused and so
this patch does the adequate cleaning when needed.
This patch fixes all the CAN drivers.
Finally, can_get_echo_skb() is decorated with the __must_check
attribute in order to force future drivers to correctly use its return
value (else the compiler would emit a warning).
[1] commit ed3320cec2 ("can: dev: __can_get_echo_skb():
fix real payload length return value for RTR frames")
Link: https://lore.kernel.org/all/20211207121531.42941-6-mailhol.vincent@wanadoo.fr
Cc: Nicolas Ferre <nicolas.ferre@microchip.com>
Cc: Alexandre Belloni <alexandre.belloni@bootlin.com>
Cc: Ludovic Desroches <ludovic.desroches@microchip.com>
Cc: Maxime Ripard <mripard@kernel.org>
Cc: Chen-Yu Tsai <wens@csie.org>
Cc: Jernej Skrabec <jernej.skrabec@gmail.com>
Cc: Yasushi SHOJI <yashi@spacecubics.com>
Cc: Oliver Hartkopp <socketcan@hartkopp.net>
Cc: Stephane Grosjean <s.grosjean@peak-system.com>
Cc: Andreas Larsson <andreas@gaisler.com>
Tested-by: Jimmy Assarsson <extja@kvaser.com> # kvaser
Signed-off-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Acked-by: Stefan Mätje <stefan.maetje@esd.eu> # esd_usb2
Tested-by: Stefan Mätje <stefan.maetje@esd.eu> # esd_usb2
[mkl: add conversion for grcan]
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
This patch adds support for a new Kvaser USB family, denoted hydra.
The hydra family currently contains USB devices with one CAN channel
up to five. There are devices with and without CAN FD support.
Signed-off-by: Jimmy Assarsson <extja@kvaser.com>
Signed-off-by: Christer Beskow <chbe@kvaser.com>
Signed-off-by: Nicklas Johansson <extnj@kvaser.com>
Signed-off-by: Martin Henriksson <mh@kvaser.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
First part of adding support for Kvaser USB device family "hydra".
Split kvaser_usb.c into kvaser_usb/kvaser_usb{.h,_core.c,_leaf.c}.
kvaser_usb_core.c contains common functionality, such as USB
writing/reading and allocation of netdev.
kvaser_usb_leaf.c contains device specific code, used in
kvaser_usb_core.c.
struct kvaser_usb_dev_ops contains device specific functions that are
common for all devices in the family. While, struct kvaser_usb_dev_cfg
describes the device configurations in terms of CAN clock frequency,
timestamp frequency and CAN controller bittiming constants.
Signed-off-by: Jimmy Assarsson <extja@kvaser.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
