Wrapping proprietary nodes

Wrapping proprietary nodes

[David VomLehn]

I expect my device tree will have some proprietary, one-off devices in
it. Is it better to wrap these all up in one node:

	cisco {
		device1 {
			...
		};
		device2 {
			...
		};
	};

Or should they be specified one node at a time:

	cisco-device1 {
		...
	};
	cisco-device2 {
		...
	};

My inclination is for the former, but I'd prefer to follow existing usage,
if any.
-- 
David VL

Re: Wrapping proprietary nodes

[David Gibson]

On Fri, Oct 22, 2010 at 02:44:54PM -0700, David VomLehn wrote:
> I expect my device tree will have some proprietary, one-off devices in
> it. Is it better to wrap these all up in one node:
> 
> 	cisco {
> 		device1 {
> 			...
> 		};
> 		device2 {
> 			...
> 		};
> 	};
> 
> Or should they be specified one node at a time:
> 
> 	cisco-device1 {
> 		...
> 	};
> 	cisco-device2 {
> 		...
> 	};
> 
> My inclination is for the former, but I'd prefer to follow existing
> usage, if any.

Um.. what do you mean by "proprietary nodes".  What is the reason from
a hardware perspective that the devices would be logically grouped
together?

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

RE: Wrapping proprietary nodes

[Yoder Stuart-B08248]

> -----Original Message-----
> From: devicetree-discuss-
> bounces+stuart.yoder=freescale.com-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org
[mailto:devicetree-
> discuss-bounces+stuart.yoder=freescale.com-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org] On Behalf
Of
> David VomLehn
> Sent: Friday, October 22, 2010 4:45 PM
> To: Device-ZEW99E7oL/EiWxQNNj96ibh/4TqKg8J2XqFh9Ls21Oc@public.gmane.org; Tree-ZEW99E7oL/EiWxQNNj96ibh/4TqKg8J2XqFh9Ls21Oc@public.gmane.org;
> Mailing-ZEW99E7oL/EiWxQNNj96ibh/4TqKg8J2XqFh9Ls21Oc@public.gmane.org; List-ZEW99E7oL/EiWxQNNj96ibh/4TqKg8J2XqFh9Ls21Oc@public.gmane.org;
> devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org
> Subject: Wrapping proprietary nodes
> 
> I expect my device tree will have some proprietary, one-off devices in
it.
> Is it better to wrap these all up in one node:
> 
> 	cisco {
> 		device1 {
> 			...
> 		};
> 		device2 {
> 			...
> 		};
> 	};
> 
> Or should they be specified one node at a time:
> 
> 	cisco-device1 {
> 		...
> 	};
> 	cisco-device2 {
> 		...
> 	};
> 
> My inclination is for the former, but I'd prefer to follow existing
usage,
> if any.

(David, long time no see...:)

The device tree should represent your hardware as it is.  If these
devices sit on some bus, then you should probably represent the
bus, with the devices as subnodes.   Don't create logical container
nodes unless they are warranted for some good reason.

Stuart

RE: Wrapping proprietary nodes

[Segher Boessenkool]

> The device tree should represent your hardware as it is.  If these
> devices sit on some bus, then you should probably represent the
> bus, with the devices as subnodes.   Don't create logical container
> nodes unless they are warranted for some good reason.

More importantly: no device tree client should ever require such
container nodes; but also every client should allow it!

No binding should require it, unless there is something really
special of course.  If you think you have such a special case:
think again.


Segher

Re: Wrapping proprietary nodes

[David VomLehn]

On Mon, Oct 25, 2010 at 11:32:46AM -0700, Yoder Stuart-B08248 wrote:
> 
> 
> > -----Original Message-----
> > From: devicetree-discuss-
> > bounces+stuart.yoder=freescale.com-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org
> [mailto:devicetree-
> > discuss-bounces+stuart.yoder=freescale.com-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org] On Behalf
> Of
> > David VomLehn
> > Sent: Friday, October 22, 2010 4:45 PM
> > To: Device-ZEW99E7oL/EiWxQNNj96ibh/4TqKg8J2XqFh9Ls21Oc@public.gmane.org; Tree-ZEW99E7oL/EiWxQNNj96ibh/4TqKg8J2XqFh9Ls21Oc@public.gmane.org;
> > Mailing-ZEW99E7oL/EiWxQNNj96ibh/4TqKg8J2XqFh9Ls21Oc@public.gmane.org; List-ZEW99E7oL/EiWxQNNj96ibh/4TqKg8J2XqFh9Ls21Oc@public.gmane.org;
> > devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org
> > Subject: Wrapping proprietary nodes
> > 
> > I expect my device tree will have some proprietary, one-off devices in
> it.
...
> > Or should they be specified one node at a time:
> > 
> > 	cisco-device1 {
> > 		...
> > 	};
> > 	cisco-device2 {
> > 		...
> > 	};
> > 
> > My inclination is for the former, but I'd prefer to follow existing
> usage,
> > if any.
> 
> (David, long time no see...:)
> 
> The device tree should represent your hardware as it is.  If these
> devices sit on some bus, then you should probably represent the
> bus, with the devices as subnodes.   Don't create logical container
> nodes unless they are warranted for some good reason.
> 
> Stuart

Makes sense. My example uses the prefix "cisco-"; does this follow common
usage?

-- 
David VL

RE: Wrapping proprietary nodes

[Yoder Stuart-B08248]

> -----Original Message-----
> From: David VomLehn [mailto:dvomlehn-FYB4Gu1CFyUAvxtiuMwx3w@public.gmane.org]
> Sent: Monday, October 25, 2010 3:41 PM
> To: Yoder Stuart-B08248
> Cc: Device-ZEW99E7oL/EiWxQNNj96ibh/4TqKg8J2XqFh9Ls21Oc@public.gmane.org; Tree-ZEW99E7oL/EiWxQNNj96ibh/4TqKg8J2XqFh9Ls21Oc@public.gmane.org;
> Mailing-ZEW99E7oL/EiWxQNNj96ibh/4TqKg8J2XqFh9Ls21Oc@public.gmane.org; List-ZEW99E7oL/EiWxQNNj96ibh/4TqKg8J2XqFh9Ls21Oc@public.gmane.org;
> devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org
> Subject: Re: Wrapping proprietary nodes
> 
> On Mon, Oct 25, 2010 at 11:32:46AM -0700, Yoder Stuart-B08248 wrote:
> >
> >
> > > -----Original Message-----
> > > From: devicetree-discuss-
> > > bounces+stuart.yoder=freescale.com-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org
> > [mailto:devicetree-
> > > discuss-bounces+stuart.yoder=freescale.com-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org] On
> > > discuss-bounces+Behalf
> > Of
> > > David VomLehn
> > > Sent: Friday, October 22, 2010 4:45 PM
> > > To: Device-ZEW99E7oL/EiWxQNNj96ibh/4TqKg8J2XqFh9Ls21Oc@public.gmane.org;
> > > Tree-ZEW99E7oL/EiWxQNNj96ibh/4TqKg8J2XqFh9Ls21Oc@public.gmane.org; Mailing-ZEW99E7oL/EiWxQNNj96ibh/4TqKg8J2XqFh9Ls21Oc@public.gmane.org;
> > > List-ZEW99E7oL/EiWxQNNj96ibh/4TqKg8J2XqFh9Ls21Oc@public.gmane.org;
devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org
> > > Subject: Wrapping proprietary nodes
> > >
> > > I expect my device tree will have some proprietary, one-off
devices
> > > in
> > it.
> ...
> > > Or should they be specified one node at a time:
> > >
> > > 	cisco-device1 {
> > > 		...
> > > 	};
> > > 	cisco-device2 {
> > > 		...
> > > 	};
> > >
> > > My inclination is for the former, but I'd prefer to follow
existing
> > usage,
> > > if any.
> >
> > (David, long time no see...:)
> >
> > The device tree should represent your hardware as it is.  If these
> > devices sit on some bus, then you should probably represent the
> > bus, with the devices as subnodes.   Don't create logical container
> > nodes unless they are warranted for some good reason.
> >
> > Stuart
> 
> Makes sense. My example uses the prefix "cisco-"; does this follow
common
> usage?

The general rule is that node names reflect the function of the device,
so
you typically wouldn't have a company name in the node name.  See
section
2.2.2 in the ePAPR, for some examples:

<http://www.power.org/resources/downloads/Power_ePAPR_APPROVED_v1.0.pdf>

For custom properties that you create, use a company specific prefix
like a stock symbol or company name (e.g. cisco,foo).

Stuart

Re: Wrapping proprietary nodes

[Grant Likely]

On Fri, Oct 22, 2010 at 02:44:54PM -0700, David VomLehn wrote:
> I expect my device tree will have some proprietary, one-off devices in
> it. Is it better to wrap these all up in one node:
> 
> 	cisco {
> 		device1 {
> 			...
> 		};
> 		device2 {
> 			...
> 		};
> 	};
> 
> Or should they be specified one node at a time:
> 
> 	cisco-device1 {
> 		...
> 	};
> 	cisco-device2 {
> 		...
> 	};
> 
> My inclination is for the former, but I'd prefer to follow existing usage,
> if any.

Neither.  The layout should reflect the actual hardware layout, and
the devices should follow the Generic Names recommended practice[1][2].

[1] http://playground.sun.com/1275/practice/gnames/gnamv14a.html
[2] http://www.power.org/resources/downloads/Power_ePAPR_APPROVED_v1.0.pdf
	section 2.2.2

The correct way to differentiate between devices (regardless of
whether or not the driver is proprietary, or if it is a custom device
for the system) is to use the 'compatible' property.  Therefore your
tree might look something like this:

	input@<address> {
		compatible = "cisco,<part/device>";
		...
	};
	dma-controller@<address> {
		compatible = "cisco,<part/device>";
		...
	};

g.


> -- 
> David VL
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