From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marc Kleine-Budde Subject: Re: CAN-FD Transceiver Limitations Date: Mon, 10 Jul 2017 16:58:28 +0200 Message-ID: <6f9f7a0b-ff9d-15bd-47be-012986a452c3@pengutronix.de> References: <20170629142142.GF9244@lunn.ch> <5d4f2bcf-bd0f-4fa1-5d5a-d7b4a83cbc5e@ti.com> <20170629154139.GC13221@lunn.ch> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="Iqx4qef1IiqKu9KNPaTs6mCbafp6NrHqs" Return-path: Received: from metis.ext.4.pengutronix.de ([92.198.50.35]:53011 "EHLO metis.ext.4.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753309AbdGJO6g (ORCPT ); Mon, 10 Jul 2017 10:58:36 -0400 In-Reply-To: <20170629154139.GC13221@lunn.ch> Sender: linux-can-owner@vger.kernel.org List-ID: To: Andrew Lunn , Franklin S Cooper Jr Cc: linux-can@vger.kernel.org, netdev@vger.kernel.org, wg@grandegger.com This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --Iqx4qef1IiqKu9KNPaTs6mCbafp6NrHqs Content-Type: multipart/mixed; boundary="PCX4K4U7FwPABNrrmrk8RTqqISHMq6cpq"; protected-headers="v1" From: Marc Kleine-Budde To: Andrew Lunn , Franklin S Cooper Jr Cc: linux-can@vger.kernel.org, netdev@vger.kernel.org, wg@grandegger.com Message-ID: <6f9f7a0b-ff9d-15bd-47be-012986a452c3@pengutronix.de> Subject: Re: CAN-FD Transceiver Limitations References: <20170629142142.GF9244@lunn.ch> <5d4f2bcf-bd0f-4fa1-5d5a-d7b4a83cbc5e@ti.com> <20170629154139.GC13221@lunn.ch> In-Reply-To: <20170629154139.GC13221@lunn.ch> --PCX4K4U7FwPABNrrmrk8RTqqISHMq6cpq Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On 06/29/2017 05:41 PM, Andrew Lunn wrote: >> Transceivers for CAN are not apart of any model. Traditional CAN didn'= t >> have a problem because all transceivers from my understanding supporte= d >> the maximum speed of 1 Mbps defined by the spec. However, with the >> introduction of CAN Flexible Datarate mode it seems that for >> transceivers that supported CAN-FD the maximum supported speeds vary. >=20 > So transceivers are dumb devices, nothing to configure, so no need to > have a driver for them. Yes and no. CAN transceivers are usually quite dumb, but most of them have some sort of "enable" pin. This pin is currently modelled as a regulator. Which fits nicely, as there dual transceivers with only one enable pin. However there are more complicated transceivers with two pins, that implement a state machine, where you can query the chip for various error conditions and can configure remote wakeup, etc... So in the future a proper driver might be implemented. Marc --=20 Pengutronix e.K. | Marc Kleine-Budde | Industrial Linux Solutions | Phone: +49-231-2826-924 | Vertretung West/Dortmund | Fax: +49-5121-206917-5555 | Amtsgericht Hildesheim, HRA 2686 | http://www.pengutronix.de | --PCX4K4U7FwPABNrrmrk8RTqqISHMq6cpq-- --Iqx4qef1IiqKu9KNPaTs6mCbafp6NrHqs Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCgAdFiEE4bay/IylYqM/npjQHv7KIOw4HPYFAlljlhQACgkQHv7KIOw4 HPbjaAf/TlYcsNitUFRD1vWPOf5wocd7lupy1uzARq0tOgIqBtRT2T2MBlYH4awM Kw26KjGP3/asGQo3/vAC3bMIfUwKEELFll6j/MNS5cBv6HQVqTZKJr6kpQkl1Trs zf+esFZRllIlxy6T+at1xWn5n7ahkHGgdYpt+YEEcdlrvG+Wsoej1wdXhpZXwcSK rd8YzQgWN8l5pNFQtdeaX9G1t2RvxgxOqv9sBTATR1OEXhzpOiiMMDdvKCIaqEcj t9KhyNLB6ZF6VEHfSzrcCbTnipRe9aeFEjo5iLFwvYTVcK8UOAqfs/2QMn0SssCU x6DxLSOfP5blM0+s8EnuEGeVya6tfw== =jNhR -----END PGP SIGNATURE----- --Iqx4qef1IiqKu9KNPaTs6mCbafp6NrHqs--