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authorDavid S. Miller <davem@davemloft.net>2012-08-08 15:55:02 -0700
committerDavid S. Miller <davem@davemloft.net>2012-08-08 15:55:02 -0700
commitd933d2beb1e416f62bf56fe002e5451414f9a9d2 (patch)
treec224370c9dee10a70f13624dd970b5dc27bcd5f3 /include
parent99aa3473e672ca610905838997fa018b95cd643f (diff)
parent035534ed3377d9def2c17717899fd64a111a785b (diff)
Merge branch 'fixes-for-3.6' of git://gitorious.org/linux-can/linux-can
Marc Kleine-Budde says: ==================== here's a fix intended for the v3.6 release cycle. Oliver noticed and fixed that the flags definition for the new canfd_frame contains redundant and confusing information. ==================== Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include')
-rw-r--r--include/linux/can.h25
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