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drivers: can: remove option for configuring CAN-FD max DLC

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Remove the Kconfig option for configuring the maximum value of the CAN-FD
Data Length Code in order to ensure standard compliance.

Allowing users to configure the max DLC allows the user to save a number of
bytes per CAN frame in RAM, but it also renders the Zephyr CAN-FD
implementation non-compliant with the CAN-FD standard.

There are no guarantees that a Zephyr CAN-FD node will not receive a CAN
frame with a DLC higher than the Kconfig limit, which opens up for all
sorts of bugs when trying to handle received CAN-FD frames.

Signed-off-by: Henrik Brix Andersen <hebad@vestas.com>
This commit is contained in:
Henrik Brix Andersen 2022-08-12 09:52:18 +02:00 • committed by Fabio Baltieri
commit c11326300f
2 changed files with 3 additions and 25 deletions
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12
drivers/can/Kconfig
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@ -54,18 +54,6 @@ config CAN_FD_MODE
help
Enable CAN-FD compatible API
if CAN_FD_MODE
config CANFD_MAX_DLC
int "Max data length code in CAN frames"
range 8 15
default 15
help
Maximum allowed DLC in a CAN frame. This parameter sets the
data buffer size in a CAN frame and is therefore only used to
optimize memory consumption.
endif # CAN_FD_MODE
config CAN_RX_TIMESTAMP
bool "Receiving timestamps"
depends on CAN_HAS_RX_TIMESTAMP

16
include/zephyr/drivers/can.h
View file

@ -52,27 +52,17 @@ extern "C" {
/**
* @brief Maximum data length code for CAN-FD.
*/
#define CANFD_MAX_DLC CONFIG_CANFD_MAX_DLC
#define CANFD_MAX_DLC 15U
/**
* @cond INTERNAL_HIDDEN
* Internally calculated maximum data length
*/
#ifndef CONFIG_CANFD_MAX_DLC
#ifndef CONFIG_CAN_FD_MODE
#define CAN_MAX_DLEN 8U
#else
#if CONFIG_CANFD_MAX_DLC <= 8
#define CAN_MAX_DLEN CONFIG_CANFD_MAX_DLC
#elif CONFIG_CANFD_MAX_DLC <= 12
#define CAN_MAX_DLEN (CONFIG_CANFD_MAX_DLC + (CONFIG_CANFD_MAX_DLC - 8U) * 4U)
#elif CONFIG_CANFD_MAX_DLC == 13
#define CAN_MAX_DLEN 32U
#elif CONFIG_CANFD_MAX_DLC == 14
#define CAN_MAX_DLEN 48U
#elif CONFIG_CANFD_MAX_DLC == 15
#define CAN_MAX_DLEN 64U
#endif
#endif /* CONFIG_CANFD_MAX_DLC */
#endif /* CONFIG_CAN_FD_MODE */
/** @endcond */