Subject: Re: [resend] Make the kernel accept ePAPR style phandle information

From: Wolfram Sang <[email-masked]>
Date: Mon, 1 Feb 2010 11:00:17 +0100

On Mon, Feb 01, 2010 at 03:52:42PM +1100, David Gibson wrote:
> Grant, I've updated this for your current test-devicetree branch.
> Please apply.
> 
> Currently when processing flattened device trees, the kernel expects
> the phandle in a property called "linux,phandle".  The ePAPR spec -
> not being Linux specific - instead requires phandles to be encoded in
> a property named simply "phandle".  This patch makes the kernel accept
> either form when unflattening the device tree.
> 
> Signed-off-by: David Gibson <[email-masked]>
> 
> Index: working-2.6/drivers/of/fdt.c
> ===================================================================
> --- working-2.6.orig/drivers/of/fdt.c	2010-02-01 15:51:44.000000000 +1100
> +++ working-2.6/drivers/of/fdt.c	2010-02-01 15:51:46.458557615 +1100
> @@ -310,10 +310,19 @@ unsigned long __init unflatten_dt_node(u
>  		pp = unflatten_dt_alloc(&mem, sizeof(struct property),
>  					__alignof__(struct property));
>  		if (allnextpp) {
> -			if (strcmp(pname, "linux,phandle") == 0) {
> +			/* We accept flattened tree phandles either in
> +			 * ePAPR-style "phandle" properties, or the
> +			 * legacy "linux,phandle" properties.  If both
> +			 * appear and have different values, things
> +			 * will get weird.  Don't do that. */

I don't want to be just pedantic, I really think the preferred way of
multi-line comments

 /*
  * foo
  * bar
  */

will help readability a lot here.

> +			if ((strcmp(pname, "phandle") == 0)
> +			    || (strcmp(pname, "linux,phandle") == 0)) {
>  				if (np->phandle == 0)
>  					np->phandle = *((u32 *)*p);
>  			}
> +			/* And we process the "ibm,phandle" property
> +			 * used in pSeries dynamic device tree
> +			 * stuff */
>  			if (strcmp(pname, "ibm,phandle") == 0)
>  				np->phandle = *((u32 *)*p);
>  			pp->name = pname;
> 
> -- 
> 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
> _______________________________________________
> Linuxppc-dev mailing list
> [email-masked]
> https://lists.ozlabs.org/listinfo/linuxppc-dev

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