From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marc Kleine-Budde Subject: Re: [PATCH 1/3] can: m_can: add Bosch M_CAN controller support Date: Thu, 03 Jul 2014 11:04:36 +0200 Message-ID: <53B51CA4.3060203@pengutronix.de> References: <1403863246-18822-1-git-send-email-b29396@freescale.com> <1403863246-18822-2-git-send-email-b29396@freescale.com> <53ADB1E8.1030504@hartkopp.net> <20140630082622.GB25689@shlinux1.ap.freescale.net> <53B4473B.2050003@hartkopp.net> <53B459C3.6070807@pengutronix.de> <20140703034839.GA20450@shlinux1.ap.freescale.net> <53B50271.8070307@pengutronix.de> <20140703084803.GA11012@shlinux1.ap.freescale.net> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="Ij2mHLF4tu7Q4KW9JHBrRlbAir2mWUakS" Return-path: In-Reply-To: <20140703084803.GA11012-KgLukfWpBlCctlrPMvKcciBecyulp+rMXqFh9Ls21Oc@public.gmane.org> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Dong Aisheng Cc: Oliver Hartkopp , linux-can-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, wg-5Yr1BZd7O62+XT7JhA+gdA@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-can.vger.kernel.org This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --Ij2mHLF4tu7Q4KW9JHBrRlbAir2mWUakS Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On 07/03/2014 10:48 AM, Dong Aisheng wrote: > On Thu, Jul 03, 2014 at 09:12:49AM +0200, Marc Kleine-Budde wrote: >> On 07/03/2014 05:48 AM, Dong Aisheng wrote: >>> On Wed, Jul 02, 2014 at 09:13:07PM +0200, Marc Kleine-Budde wrote: >>>> On 07/02/2014 07:54 PM, Oliver Hartkopp wrote: >>>>> I'm not really familiar with the naming concept in device trees. >>>>> >>>>> What is your opinion about the remarks below? >>>> >>>> The entries in the DT, at least on freescale baords, follow the nami= ng >>>> scheme of the reference manual. E.g. on the mx25 it's can1 and can2:= >>>> >>>> can1: can@43f88000 { ... } >>>> can2: can@43f8c000 { ... } >>>> >>>> And on the mx28, its: >>>> >>>> can0: can@80032000 { ... } >>>> can1: can@80034000 { ... } >>>> >>>> Because the imx25 datasheet uses a "1" based counting scheme, while = the >>>> imx28 uses a "0" based one. >>>> >>>> So it's best practise to follow the naming and numbering scheme of t= he >>>> hardware reference manual.....and if you have access to the >>>> documentation of the m_can core, use clock names of the m_can core f= or >>>> the clock-names property. >>>> >>> >>> Based on my knowledge, device tree allows define phandle name accordi= ng to >>> the real device name of HW according spec while the device node name = should >>> be general(e.g can@80032000 rather than flexcan@80032000). >>> For imx6sx, there are already following entries in >>> arch/arm/boot/dts/imx6sx.dtsi >>> flexcan1: can@02090000 {...} >>> flexcan2: can@02094000 {...} >>> So i'd prefer to define as: >>> m_can1: canfd@020e8000 {...} >>> m_can2: canfd@020f0000 {...} >>> >>> >>> One problem is there're can alias already. >>> aliases { >>> can0 =3D &flexcan1; >>> can1 =3D &flexcan2; >>> ... >>> } >>> I'm not sure adding can2&can3 for mcan is properly: >>> aliases { >>> can0 =3D &flexcan1; >>> can1 =3D &flexcan2; >>> can2 =3D &m_can1; >>> can3 =3D &m_can2; >>> ... >>> } >>> Since the m_can driver does not need to use aliases, >>> so i will not add them. >> >> IMHO It's fine too add the can{2,3} aliases to m_can, too. >> >=20 > I think the main problem for doing this way is that the meaning of id > return by of_alias_get_id may be not persistent. > e.g > For MX6SX > aliases { > can0 =3D &flexcan1; > can1 =3D &flexcan2; > can2 =3D &m_can1; > can3 =3D &m_can2; > ... > } >=20 > For other platform, it could be: > aliases { > can0 =3D &m_can1; > can1 =3D &m_can2; > ... > } > It's hard for driver to use. The driver doesn't make use of it, does it? > And actually the M_CAN driver does not need to use the alias. > So i wonder if it makes sense to add the alias for m_can devices > like that. For example the imx53 has two different SPI units, in the alias section we see: spi0 =3D &ecspi1; spi1 =3D &ecspi2; spi2 =3D &cspi; 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 | --Ij2mHLF4tu7Q4KW9JHBrRlbAir2mWUakS Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 Comment: Using GnuPG with Icedove - http://www.enigmail.net/ iEYEARECAAYFAlO1HKQACgkQjTAFq1RaXHPLNQCgiZ0vFUqmCl4uztSf2usSOYin KB0AnjnA8TEjnRSDEWjdPmgIB0TPX1uM =5K2c -----END PGP SIGNATURE----- --Ij2mHLF4tu7Q4KW9JHBrRlbAir2mWUakS-- -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html