From mboxrd@z Thu Jan 1 00:00:00 1970 From: Oliver Hartkopp Subject: Re: [PATCH v2 2/4] can: fixed-transceiver: Add documentation for CAN fixed transceiver bindings Date: Fri, 28 Jul 2017 10:41:40 +0200 Message-ID: References: <20170724230521.1436-1-fcooper@ti.com> <20170724230521.1436-3-fcooper@ti.com> <20170726164124.GL12049@lunn.ch> <355b90b3-97ce-1057-6617-d5d709449c48@hartkopp.net> <932602fe-d06a-7a17-5a0c-24265cf2e643@ti.com> <20170728045724.GA27903@airbook.vandijck-laurijssen.be> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20170728045724.GA27903@airbook.vandijck-laurijssen.be> Sender: linux-can-owner@vger.kernel.org To: Franklin S Cooper Jr , Andrew Lunn , linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, netdev@vger.kernel.org, linux-can@vger.kernel.org, wg@grandegger.com, mkl@pengutronix.de, robh+dt@kernel.org, quentin.schulz@free-electrons.com, sergei.shtylyov@cogentembedded.com List-Id: devicetree@vger.kernel.org On 07/28/2017 06:57 AM, Kurt Van Dijck wrote: > So while _a_ transceiver may be spec'd to 1MBit during arbitration, > CAN FD packets may IMHO exceed that speed during data phase. When the bitrate is limited to 1Mbit/s you are ONLY allowed to use 1Mbit/s in the data section too (either with CAN or CAN FD). > That was the whole point of CAN FD: exceed the limits required for > correct arbitration on transceiver & wire. No. CAN FD is about a different frame format with up to 64 bytes AND the possibility to increase the bitrate in the data section of the frame. > So I do not agree on the single bandwidth limitation. The transceiver provides a single maximum bandwidth. It's an ISO Layer 1 device. > The word 'max-arbitration-bitrate' makes the difference very clear. I think you are mixing up ISO layer 1 and ISO layer 2. Regards, Oliver