On Tue, Aug 09, 2011 at 12:41:39PM +0000, U Bhaskar-B22300 wrote: > > > > -----Original Message----- > > From: Wolfgang Grandegger [mailto:[email protected]] > > Sent: Tuesday, August 09, 2011 4:19 PM > > To: U Bhaskar-B22300 > > Cc: Marc Kleine-Budde; [email protected]; > > [email protected]; [email protected] > > 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:[email protected]] > > >> Sent: Tuesday, August 09, 2011 2:03 PM > > >> To: U Bhaskar-B22300 > > >> Cc: Marc Kleine-Budde; [email protected]; > > >> [email protected]; [email protected] > > >> 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:[email protected]] > > >>>> Sent: Tuesday, August 09, 2011 12:23 AM > > >>>> To: Wolfgang Grandegger > > >>>> Cc: [email protected]; [email protected]; 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. Thanks, Robin _______________________________________________ Socketcan-core mailing list [email protected] https://lists.berlios.de/mailman/listinfo/socketcan-core
