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Message-ID: <20110810184538.GA4926@sgi.com>
Date: Wed, 10 Aug 2011 13:45:38 -0500
From: Robin Holt <holt@....com>
To: Scott Wood <scottwood@...escale.com>
Cc: Robin Holt <holt@....com>, Kumar Gala <galak@...nel.crashing.org>,
Wolfgang Grandegger <wg@...ndegger.com>,
U Bhaskar-B22300 <B22300@...escale.com>,
Grant Likely <grant.likely@...retlab.ca>,
Marc Kleine-Budde <mkl@...gutronix.de>,
socketcan-core@...ts.berlios.de, netdev@...r.kernel.org,
PPC list <linuxppc-dev@...ts.ozlabs.org>,
devicetree-discuss@...ts.ozlabs.org
Subject: Re: [PATCH v11 5/5] powerpc: Fix up fsl-flexcan device tree
binding.
On Wed, Aug 10, 2011 at 01:40:30PM -0500, Scott Wood wrote:
> On 08/10/2011 01:30 PM, Robin Holt wrote:
> > On Wed, Aug 10, 2011 at 12:36:22PM -0500, Scott Wood wrote:
> >> On 08/10/2011 12:19 PM, Robin Holt wrote:
> >>> On Wed, Aug 10, 2011 at 11:56:28AM -0500, Scott Wood wrote:
> >>>> Also may want to list fsl,p1010-rdb as a "canonical compatible" for
> >>>> anything which is backwards compatible with p1010's implementation.
> >>>
> >>> How do I specify 'canonical compatible'?
> >>
> >> Something like:
> >>
> >> compatible: Should be "fsl,<processor>-flexcan" and "fsl,flexcan".
> >>
> >> An implementation should also claim any of the following compatibles
> >> that it is fully backwards compatible with:
> >>
> >> - fsl,p1010-rdb
>
> Gah, I don't know how "rdb" replaced "flexcan" in the above. Sorry for
> any confusion.
>
> > I am so confused. fsl,p1010-flexcan refers, in my mind at least, to
> > a particular chiplet on the p1010 freescale processor.
>
> It refers to a particular version of the flexcan logic, for which the
> hardware doc people weren't kind enough to give us a public version number.
>
> It has been common and recommended practice in such cases, when there
> are multiple chips containing the same device, to pick a canonical chip
> (such as the first one to have the device or to be supported) and have
> others claim compatibility with it.
>
> > fsl,p1010-rdb
> > would mean nothing to me as that is a p1010 processor with two flexcan
> > chiplets wired to a pair of DB-9 jacks. For the driver, what additional
> > information is being conveyed?
>
> The programming model of the flexcan chiplet.
>
> > Let's cut to the chase. Here is what I have after incorporating your
> > earlier comment about the compatible line. Please mark this up to
> > exactly what you are asking for.
> >
> > Thanks,
> > Robin
> > ------------------------------------------------------------------------
> > Flexcan CAN contoller on Freescale's ARM and PowerPC processors
> >
> > Required properties:
> >
> > - compatible : Should be "fsl,<processor>-flexcan" and "fsl,flexcan"
>
> An implementation should also claim any of the following compatibles
> that it is fully backwards compatible with:
>
> - fsl,p1010-flexcan
Ah, there is my confusion. I did not realize you were saying the
entire preceeding 4 lines should be included. I thought you were
making a comment which I did not understand.
Thank you for your patience with my ignorance,
Robin
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