From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mark Rutland Subject: Re: [Patch V2 4/4] ARM: dts: AM33XX: update rtc node compatibility Date: Fri, 2 Aug 2013 13:40:33 +0100 Message-ID: <20130802124033.GL2884@e106331-lin.cambridge.arm.com> References: <1372841225-18813-1-git-send-email-gururaja.hebbar@ti.com> <1372841225-18813-5-git-send-email-gururaja.hebbar@ti.com> <51F749B0.7020802@ti.com> <20130730145501.GA29859@e106331-lin.cambridge.arm.com> <51F7E7FA.3080702@ti.com> <20130801170537.GF8095@e106331-lin.cambridge.arm.com> <51FB92F8.9020801@ti.com> <20130802112018.GI2884@e106331-lin.cambridge.arm.com> <51FB9C77.3090202@ti.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <51FB9C77.3090202@ti.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=m.gmane.org@lists.infradead.org To: Gururaja Hebbar Cc: "davinci-linux-open-source@linux.davincidsp.com" , "tony@atomide.com" , "benoit.cousson@gmail.com" , Sekhar Nori , "linux-kernel@vger.kernel.org" , "vaibhav.bedia@ti.com" , "benoit.cousson@linaro.org" , "linux-omap@vger.kernel.org" , "devicetree-discuss@lists.ozlabs.org" , "linux-arm-kernel@lists.infradead.org" List-Id: devicetree@vger.kernel.org On Fri, Aug 02, 2013 at 12:48:07PM +0100, Gururaja Hebbar wrote: > On 8/2/2013 4:50 PM, Mark Rutland wrote: > > On Fri, Aug 02, 2013 at 12:07:36PM +0100, Gururaja Hebbar wrote: > >> On 8/1/2013 10:35 PM, Mark Rutland wrote: > >>> On Tue, Jul 30, 2013 at 05:21:14PM +0100, Sekhar Nori wrote: > >>>> On 7/30/2013 8:25 PM, Mark Rutland wrote: > >>>>> On Tue, Jul 30, 2013 at 06:05:52AM +0100, Gururaja Hebbar wrote: > >>>>>> Hi, > >>>>>> > >>>>>> On 7/3/2013 2:17 PM, Hebbar Gururaja wrote: > >>>>>>> Since AM33xx RTC IP has RTC_IRQWAKEEN to support Alarm Wake-up. > >>>>>>> > >>>>>>> Update the rtc compatible property to "ti,am3352-rtc" to enable handling > >>>>>>> of this feature inside rtc-omap driver. > >>>>>> > >>>>>> The other 2 rtc driver related patches have been pulled up. If you have > >>>>>> no comments, can you please pull this up. > >>>>>> > >>>>>> Regards > >>>>>> Gururaja > >>>>>> > >>>>>>> > >>>>>>> Signed-off-by: Hebbar Gururaja > >>>>>>> --- > >>>>>>> :100644 100644 77aa1b0... dde180a... M arch/arm/boot/dts/am33xx.dtsi > >>>>>>> arch/arm/boot/dts/am33xx.dtsi | 2 +- > >>>>>>> 1 file changed, 1 insertion(+), 1 deletion(-) > >>>>>>> > >>>>>>> diff --git a/arch/arm/boot/dts/am33xx.dtsi b/arch/arm/boot/dts/am33xx.dtsi > >>>>>>> index 77aa1b0..dde180a 100644 > >>>>>>> --- a/arch/arm/boot/dts/am33xx.dtsi > >>>>>>> +++ b/arch/arm/boot/dts/am33xx.dtsi > >>>>>>> @@ -297,7 +297,7 @@ > >>>>>>> }; > >>>>>>> > >>>>>>> rtc@44e3e000 { > >>>>>>> - compatible = "ti,da830-rtc"; > >>>>>>> + compatible = "ti,am3352-rtc"; > >>>>> > >>>>> Given that this is backwards compatible with the old binding, it would > >>>>> be nicer to have this as: > >>>>> > >>>>> compatible = "ti,am3352-rtc", "ti,da830-rtc"; > >>>>> > >>>>> We must get into the habit of changing dts files in a > >>>>> backwards-compatible fashion. > >>>> > >>>> Right, I suggested this when v1 was posted. It turns out the current > >>>> kernel does not handle the compatilble list correctly and the string > >>>> selected actually depends on the order in which it appears in match > >>>> table in driver instead. > >>>> > >>>> I saw there were patches being discussed to fix this issue, but until > >>>> that is fixed, we cannot really use what you (and I before) suggested. > >>> > >>> A temporary solution would be to list the "ti,am3352-rtc" first in the > >>> of_match_table kernel-side. > >> > >> If above method is followed, then it would cause trouble on davinci > >> platform because this rtc-omap driver is also used by Davinci platform. > >> On davinci Plaform the driver would match with "ti,am3352-rtc" for > >> compatible. > > > > Sorry, I don't follow. Does the davinci dt have "ti,am3352-rtc" in it's > > compatible string list? > > no no. Davinci .dts uses "ti,da830-rtc". Ok. > > I was saying if we reverse the order of "of_device_id" structure in > rtc-omap driver, then it would work nicely for am335x but will cause > trouble on davinci platform. I don't understand. If we place "ti,am3352-rtc" first in the list, it won't be match the davinci dts compatible string, and the code will go over the of_device_id entires until it finds the "ti,da830-rtc" entry used by davinci. What problem would this cause, and why? Thanks, Mark. > > > > > If so, and it's not compatible, the dts is wrong. > > > > If not, then we won't use the behaviour specific to "ti,am3352-rtc", and > > there's no problem. > > > > What trouble would this cause? > > > > Thanks, > > Mark. > > > >> > >> Regards > >> Gururaja > >> > >>> That way you can keep the old compatible > >>> string in the dts compatible list, and maintain backwards compatibilty > >>> with older kernels. > >>> > >>> Later if the way Linux matches compatible strings is changed, this > >>> shouldn't break the probe order, and the of_match_table order could be > >>> changed. > >>> > >>> Have I missed something? > >>> > >>> Thanks, > >>> Mark. > >>> > >> > >> > >> _______________________________________________ > >> linux-arm-kernel mailing list > >> linux-arm-kernel@lists.infradead.org > >> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel > >> > > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel >