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Re: Device Tree questions WRT MIPS/Octeon SOCs.

To: "David VomLehn (dvomlehn)" <dvomlehn@cisco.com>
Subject: Re: Device Tree questions WRT MIPS/Octeon SOCs.
From: Grant Likely <grant.likely@secretlab.ca>
Date: Fri, 15 Oct 2010 21:48:50 -0600
Cc: Warner Losh <imp@bsdimp.com>, ddaney@caviumnetworks.com, prasun.kapoor@caviumnetworks.com, linux-mips@linux-mips.org, devicetree-discuss@lists.ozlabs.org
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On Fri, Oct 15, 2010 at 12:30:48PM -0500, David VomLehn (dvomlehn) wrote:
> If this is really a question of needing to dynamically generate the
> device tree, then you have no choice. It's worth mentioning, though,
> that the device tree compiler (dtc) does have the ability to include
> files, making it easier to create and maintain device trees that are
> static but which share devices.

Yes.  In fact, John Bonesio is working right now of polishing the last
details of this to allow for example a board-level .dts file to
include an SoC level .dts and add/remove/modify nodes as needed.
Should be sorted out in a week or two.  Once that is done then we'll
update the copy of dtc in the kernel (probably looking at the 2.6.38
timeframe realistically).

g.

> 
> > -----Original Message-----
> > From: linux-mips-bounce@linux-mips.org [mailto:linux-mips-bounce@linux-
> > mips.org] On Behalf Of Grant Likely
> > Sent: Thursday, October 14, 2010 6:29 PM
> > To: Warner Losh
> > Cc: ddaney@caviumnetworks.com; prasun.kapoor@caviumnetworks.com; linux-
> > mips@linux-mips.org; devicetree-discuss@lists.ozlabs.org
> > Subject: Re: Device Tree questions WRT MIPS/Octeon SOCs.
> > 
> > On Thu, Oct 14, 2010 at 7:13 PM, Warner Losh <imp@bsdimp.com> wrote:
> > > In message: <AANLkTi=UM2p26JJMqv-
> > cNh8xACS_KPf_dCst5cgmh5VR@mail.gmail.com>
> > >            Grant Likely <grant.likely@secretlab.ca> writes:
> > > : Overall the plan makes sense, however I would suggest the
> > following.
> > > : instead of 'live' modifying the tree, another option is to carry a
> > set
> > > : of 'stock' device trees in the kernel; one per board.  Of course
> > this
> > > : assumes that your current ad-hoc code is keying on the specific
> > board.
> > > :  If it is interpreting data provided by the firmware, then your
> > > : suggestion of modifying a single stock tree probably makes more
> > sense,
> > > : or possibly a combination of the too.  In general you should avoid
> > > : live modification as much as possible.
> > >
> > > The one draw back on this is that there's lots of different "stock"
> > > boards that the Cavium Octeon SDK supports.  These will be difficult
> > > to drag along for every kernel.  And they'd be mostly the same to,
> > > which is why I think that David is suggesting the live modification
> > > thing...
> > 
> > Okay.  Do what makes the most sense for your platform.
> > 
> > g.
> 

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