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Message-ID: <20110809133531.GV4926@sgi.com> Date: Tue, 9 Aug 2011 08:35:31 -0500 From: Robin Holt <holt@....com> To: Wolfgang Grandegger <wg@...ndegger.com> Cc: Robin Holt <holt@....com>, U Bhaskar-B22300 <B22300@...escale.com>, "socketcan-core@...ts.berlios.de" <socketcan-core@...ts.berlios.de>, "netdev@...r.kernel.org" <netdev@...r.kernel.org>, "Devicetree-discuss@...ts.ozlabs.org" <Devicetree-discuss@...ts.ozlabs.org>, Marc Kleine-Budde <mkl@...gutronix.de> Subject: Re: [RFC 5/5] [powerpc] Implement a p1010rdb clock source. On Tue, Aug 09, 2011 at 03:03:50PM +0200, Wolfgang Grandegger wrote: > On 08/09/2011 02:49 PM, Robin Holt wrote: > > On Tue, Aug 09, 2011 at 12:41:39PM +0000, U Bhaskar-B22300 wrote: > >> > >> > >>> -----Original Message----- > >>> From: Wolfgang Grandegger [mailto:wg@...ndegger.com] > >>> Sent: Tuesday, August 09, 2011 4:19 PM > >>> To: U Bhaskar-B22300 > >>> Cc: Marc Kleine-Budde; socketcan-core@...ts.berlios.de; > >>> netdev@...r.kernel.org; Devicetree-discuss@...ts.ozlabs.org > >>> Subject: Re: [RFC 5/5] [powerpc] Implement a p1010rdb clock source. > >>> > >>> On 08/09/2011 11:27 AM, U Bhaskar-B22300 wrote: > >>>> > >>>> > >>>>> -----Original Message----- > >>>>> From: Wolfgang Grandegger [mailto:wg@...ndegger.com] > >>>>> Sent: Tuesday, August 09, 2011 2:03 PM > >>>>> To: U Bhaskar-B22300 > >>>>> Cc: Marc Kleine-Budde; socketcan-core@...ts.berlios.de; > >>>>> netdev@...r.kernel.org; Devicetree-discuss@...ts.ozlabs.org > >>>>> Subject: Re: [RFC 5/5] [powerpc] Implement a p1010rdb clock source. > >>>>> > >>>>> Hi Bhaskar, > >>>>> > >>>>> On 08/09/2011 09:57 AM, U Bhaskar-B22300 wrote: > >>>>>> > >>>>>> > >>>>>>> -----Original Message----- > >>>>>>> From: Marc Kleine-Budde [mailto:mkl@...gutronix.de] > >>>>>>> Sent: Tuesday, August 09, 2011 12:23 AM > >>>>>>> To: Wolfgang Grandegger > >>>>>>> Cc: socketcan-core@...ts.berlios.de; netdev@...r.kernel.org; U > >>>>>>> Bhaskar- B22300 > >>>>>>> Subject: Re: [RFC 5/5] [powerpc] Implement a p1010rdb clock source. > >>>>>>> > >>>>>>> On 08/08/2011 05:33 PM, Wolfgang Grandegger wrote: > >>>>>>>>> ACK - The device tree bindings as in mainline's Documentation is > >>>>>>>>> a > >>>>>>> mess. > >>>>>>>>> If the powerpc guys are happy with a clock interfaces based > >>>>>>>>> approach somewhere in arch/ppc, I'm more than happy to remove: > >>>>>>>>> - fsl,flexcan-clock-source (not implemented, even in the fsl > >>>>>>>>> driver) > >>>>>> [Bhaskar]I have pushed the FlexCAN series of patches, It contains > >>>>>> the usage of all the fields posted in the FlexCAN bindings at > >>>>>> http://git.kernel.org/?p=linux/kernel/git/stable/linux-3.0.y.git;a=b > >>>>>> lo > >>>>>> b;f=Documentation/devicetree/bindings/net/can/fsl-flexcan.txt;h=1a72 > >>>>>> 9f > >>>>>> 089866259ef82d0db5893ff7a8c54d5ccf;hb=94ed5b4788a7cdbe68bc7cb8516972 > >>>>>> cb > >>>>>> ebdc8274 > >>>>> > >>>>> As Marc already pointed out, Robin already has a much more advanced > >>>>> patch stack in preparation. Especially your patches do not care about > >>>>> the already existing Flexcan core on the Freescale's ARM socks. > >>>> [Bhaskar] No, the patches are taking care of the existing ARM > >>> functionality. > >>>> I have not tested on the ARM based board, but the patches are made > >>> in a > >>>> Manner that it should not break the ARM based functionality. > >>>>> > >>>>>>>>> > >>>>>>>>> - fsl,flexcan-clock-divider \__ replace with code in arch/ppc, or > >>>>>>>>> - clock-frequency / a single clock-frequency attribute > >>>>>>>> > >>>>>>>> In the "net-next-2.6" tree there is also: > >>>>>>>> > >>>>>>>> $ grep flexcan arch/powerpc/boots/dts/*.dts > >>>>>>>> p1010rdb.dts: fsl,flexcan-clock-source = > >>>>> "platform"; > >>>>>>>> p1010rdb.dts: fsl,flexcan-clock-source = > >>>>> "platform"; > >>>>>>>> p1010si.dtsi: compatible = "fsl,flexcan-v1.0"; > >>>>>>>> p1010si.dtsi: fsl,flexcan-clock-divider = <2>; > >>>>>>>> p1010si.dtsi: compatible = "fsl,flexcan-v1.0"; > >>>>>>>> p1010si.dtsi: fsl,flexcan-clock-divider = <2>; > >>>>>>>> > >>>>>>>> Especially the fsl,flexcan-clock-divider = <2>; might make people > >>>>>>>> think, that they could set something else. > >>>>>>> > >>>>>> [Bhaskar] As it is mentioned in the Flexcan bindings, the need of > >>>>> fsl,flexcan-clock-divider = <2>; > >>>>>> But I kept it as "2" because FlexCan clock source is the > >>>>> platform clock and it is CCB/2 > >>>>>> If the "2" is misleading, the bindings can be changed or some > >>>>> text can be written to make the meaning of "2" > >>>>>> Understandable , Please suggest .. > >>>>> > >>>>> The clock source and frequency is fixed. Why do we need an extra > >>>>> properties for that. We have panned to remove these bogus bindings > >>>>> from the Linux kernel, which sneaked in *without* any review on the > >>>>> relevant mailing lists (at least I have not realized any posting). We > >>>>> do not think they are really needed. They just confuse the user. We > >>>>> also prefer to use the compatibility string "fsl,flexcan" instead > >>>>> "fsl,flexcan-v1.0". It's unusual to add a version number, which is > >>>>> for the Flexcan on the PowerPC cores only, I assume, but there will > >>>>> be device tree for ARM soon. A proper compatibility string would be > >>>>> "fsl,p1010-flexcan" if we really need to distinguish. > >>>>> > >>>> [Bhaskar] About clock source.. There can be two sources of clock for > >>> the CAN. > >>>> Oscillator or the platform clock, but at present only platform > >>> clock is supported > >>>> in P1010.If we remove the fsl,flexcan-clock-source property, we > >>> will lost the flexibility > >>>> of changing the clock source .. > >>>> > >>>> About clock-frequency... it is also not fixed. It depends on > >>> the platform clock which in turns > >>>> Depends on the CCB clock. So it will be better to keep clock- > >>> frequency property which is getting fixed via u-boot. > >>> > >>> The frequency is fixed to CCB-frequency / 2. Will that ever change? What > >>> can we expect from future Flexcan hardware? Will it support further clock > >>> sources? > >> [Bhaskar] Yes the frequency will always be CCB-frequency/2.Even if the CCB gets changed that will be taken care by the u-boot fixup code for > >> clock-frequency. clock-frequency is not filled by somebody in the dts file. It will be done by u-boot. > >> For clock source,I can't say right now, that's why I have kept a property for this in the can node. So that in future, we need to fill it > >> appropriately > > > > Speaking of the dts file, I have left the p1010si.dtsi file with > > the fsl,flexcan-v1.0 .compatible definition. The flexcan folks > > (IIRC Wolfgang) objected to that as it does not follow the standard > > which should be just fsl,flexcan. > > > > How would you like to change that? Should I add it as part of this patch, > > add another patch to the series, or let you take care of it? > > > > Also, I assume the uboot project will need to be changed as well to > > reflect the corrected name. > > I think you should provide patches within this series to cleanup the > obsolete stuff, dts and binding doc. It reads to me that the binding doc now reduces just the required properties. Should I remove the file entirely? Robin -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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