diff options
| -rw-r--r-- | include/linux/can.h | 25 |
1 files changed, 13 insertions, 12 deletions
diff --git a/include/linux/can.h b/include/linux/can.h index 018055efc03..e52958d7c2d 100644 --- a/include/linux/can.h +++ b/include/linux/can.h @@ -74,20 +74,21 @@ struct can_frame { /* * defined bits for canfd_frame.flags * - * As the default for CAN FD should be to support the high data rate in the - * payload section of the frame (HDR) and to support up to 64 byte in the - * data section (EDL) the bits are only set in the non-default case. - * Btw. as long as there's no real implementation for CAN FD network driver - * these bits are only preliminary. + * The use of struct canfd_frame implies the Extended Data Length (EDL) bit to + * be set in the CAN frame bitstream on the wire. The EDL bit switch turns + * the CAN controllers bitstream processor into the CAN FD mode which creates + * two new options within the CAN FD frame specification: * - * RX: NOHDR/NOEDL - info about received CAN FD frame - * ESI - bit from originating CAN controller - * TX: NOHDR/NOEDL - control per-frame settings if supported by CAN controller - * ESI - bit is set by local CAN controller + * Bit Rate Switch - to indicate a second bitrate is/was used for the payload + * Error State Indicator - represents the error state of the transmitting node + * + * As the CANFD_ESI bit is internally generated by the transmitting CAN + * controller only the CANFD_BRS bit is relevant for real CAN controllers when + * building a CAN FD frame for transmission. Setting the CANFD_ESI bit can make + * sense for virtual CAN interfaces to test applications with echoed frames. */ -#define CANFD_NOHDR 0x01 /* frame without high data rate */ -#define CANFD_NOEDL 0x02 /* frame without extended data length */ -#define CANFD_ESI 0x04 /* error state indicator */ +#define CANFD_BRS 0x01 /* bit rate switch (second bitrate for payload data) */ +#define CANFD_ESI 0x02 /* error state indicator of the transmitting node */ /** * struct canfd_frame - CAN flexible data rate frame structure |