From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ray Jui Subject: Re: [PATCH v4 3/3] ARM: dts: add I2C device nodes for Broadcom Cygnus Date: Fri, 16 Jan 2015 15:18:12 -0800 Message-ID: <54B99C34.3040106@broadcom.com> References: <1421274213-3544-1-git-send-email-rjui@broadcom.com> <1421274213-3544-4-git-send-email-rjui@broadcom.com> <20150115084456.GO22880@pengutronix.de> <54B96559.1010007@broadcom.com> <20150116194831.GV22880@pengutronix.de> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <20150116194831.GV22880-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: =?windows-1252?Q?Uwe_Kleine-K=F6nig?= Cc: Wolfram Sang , Rob Herring , Pawel Moll , Mark Rutland , Ian Campbell , Kumar Gala , Grant Likely , Christian Daudt , Matt Porter , Florian Fainelli , Russell King , Scott Branden , linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, bcm-kernel-feedback-list-dY08KVG/lbpWk0Htik3J/w@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-i2c@vger.kernel.org On 1/16/2015 11:48 AM, Uwe Kleine-K=F6nig wrote: > Hello, >=20 > On Fri, Jan 16, 2015 at 11:24:09AM -0800, Ray Jui wrote: >>>> + i2c0: i2c@18008000 { >>>> + compatible =3D "brcm,iproc-i2c"; >>> in patch 2 you wrote the driver is for a family of SoCs, right? The= n I'd >>> make this: >>> >>> compatible =3D "brcm,$mysoc-iproc-i2c", "brcm,iproc-i2c"; >>> >> Sorry could you please help to explain the intention here? Note the >> iProc I2C IP can be found in various iProc family of SoCs, but to my >> best knowledge, there hasn't been any changes of the IP in any of th= ose >> SoCs. > This is just for making the device tree stable in the future. Conside= r > your gentle hardware engineers "fix" a small issue for the next > generation iproc SoC "pony" that needs an incompatible software chang= e. >=20 > Then you can fix the driver without updating the device trees by > switching to the SoC specific compatible string for "pony". And in ca= se > the hardware engineers didn't tell you that there is a change and the > need for the software change is only detected when the machines are > already shipped, you're happy if you can fix your kernel without need= ing > to change the bootloader that provides the dtb. > So start already today to add the (for now unused) compatible string. >=20 >> Is the compatible ID "brcm,$mysoc-iproc-i2c" only to clarify that it= 's >> for a specific SoC? If so, what should the compatible ID array look >> like? Should it be changed to the following? >> >> static const struct of_device_id bcm_iproc_i2c_of_match[] =3D { >> { .compatible =3D "brcm,iproc-i2c" }, >> { .compatible =3D "brcm,$mysoc-iproc-i2c" }, >> {}, >> }; > No, there is no need, see above. >=20 > If something is still unclear, don't hesitate to ask. >=20 > Best regards > Uwe >=20 Okay got it. Thanks for the explanation! -- To unsubscribe from this list: send the line "unsubscribe devicetree" i= n the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html