diff options
Diffstat (limited to 'include/uapi/linux/can.h')
| -rw-r--r-- | include/uapi/linux/can.h | 13 |
1 files changed, 11 insertions, 2 deletions
diff --git a/include/uapi/linux/can.h b/include/uapi/linux/can.h index c7535352fef6..90801ada2bbe 100644 --- a/include/uapi/linux/can.h +++ b/include/uapi/linux/can.h @@ -123,8 +123,8 @@ struct can_frame { /* * defined bits for canfd_frame.flags * - * 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 use of struct canfd_frame implies the FD Frame (FDF) bit to + * be set in the CAN frame bitstream on the wire. The FDF bit switch turns * the CAN controllers bitstream processor into the CAN FD mode which creates * two new options within the CAN FD frame specification: * @@ -135,9 +135,18 @@ struct can_frame { * 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. + * + * The struct can_frame and struct canfd_frame intentionally share the same + * layout to be able to write CAN frame content into a CAN FD frame structure. + * When this is done the former differentiation via CAN_MTU / CANFD_MTU gets + * lost. CANFD_FDF allows programmers to mark CAN FD frames in the case of + * using struct canfd_frame for mixed CAN / CAN FD content (dual use). + * N.B. the Kernel APIs do NOT provide mixed CAN / CAN FD content inside of + * struct canfd_frame therefore the CANFD_FDF flag is disregarded by Linux. */ #define CANFD_BRS 0x01 /* bit rate switch (second bitrate for payload data) */ #define CANFD_ESI 0x02 /* error state indicator of the transmitting node */ +#define CANFD_FDF 0x04 /* mark CAN FD for dual use of struct canfd_frame */ /** * struct canfd_frame - CAN flexible data rate frame structure |