From aecd89e85534d31b161bbe16e31d98f67947e1eb Mon Sep 17 00:00:00 2001 From: Stefan Tatschner Date: Tue, 24 Nov 2015 15:06:29 +0100 Subject: [PATCH] can-doc: Add hint about getting timestamps This patch adds a hint about how to get timestamps of received CAN frames with ioctl(2). This hint has been applied to the former SocketCAN Documentation, but it got lost during mainlining the first bits and pieces to linux kernel. Signed-off-by: Stefan Tatschner Signed-off-by: Jonathan Corbet --- Documentation/networking/can.txt | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/Documentation/networking/can.txt b/Documentation/networking/can.txt index 05fd83bb3596..6ab619fcc517 100644 --- a/Documentation/networking/can.txt +++ b/Documentation/networking/can.txt @@ -372,6 +372,15 @@ solution for a couple of reasons: nbytes = sendto(s, &frame, sizeof(struct can_frame), 0, (struct sockaddr*)&addr, sizeof(addr)); + An accurate timestamp can be obtained with an ioctl(2) call after reading + a message from the socket: + + struct timeval tv; + ioctl(s, SIOCGSTAMP, &tv); + + The timestamp has a resolution of one microsecond and is set automatically + at the reception of a CAN frame. + Remark about CAN FD (flexible data rate) support: Generally the handling of CAN FD is very similar to the formerly described -- 2.45.2