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Subject: Re: [PATCH] PowerMac11,2 i2c-bus@0 duplicate dev-tree workaround
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Johannes Berg <johannes@sipsolutions.net>
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Date: Thu, 30 Mar 2006 15:26:04 +1100
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> +		/* so if the workaround is in effect, and we have the right
> +		 * node found, we increase the workaround count (we use the
> +		 * same variable) and then set allnextpp to NULL on the second
> +		 * one around so the node isn't added to the allnodes list */
> +		if (powermac_i2c_bus_0_workaround &&
> +		    strcmp(np->full_name,
> +		           "/ht@0,f2000000/pci@8/mac-io@7/i2c@18000/i2c-bus@0") == 0) {
> +			powermac_i2c_bus_0_workaround++;
> +			if (powermac_i2c_bus_0_workaround == 3)
> +				allnextpp = NULL;
> +		}
> +		if (allnextpp) {
> +			**allnextpp = np;
> +			*allnextpp = &np->allnext;
> +			if (dad != NULL) {
> +				np->parent = dad;
> +				/* we temporarily use the next field as `last_child'*/
> +				if (dad->next == 0)
> +					dad->child = np;
> +				else
> +					dad->next->sibling = np;
> +				dad->next = np;
> +			}
>  		}
>  		kref_init(&np->kref);
>  	}

Hrm... you set allnextpp to NULL ... won't that prevent any further node
from being enqueued in the global node list ?

In fact, I think the workaround should be in prom_init.c when
flattening... easier to skip a node there, and that's also where you are
reasonably sure of getting the nodes in the right order, not when
unflattening. 

Also, you don't even need to test for PowerMac11,2 .. .prom_init.c
already has a machine type, so just test that it's a mac and has this
node duplicated, and if yes, remove the dup. In fact, you could probably
even run a bit of forth with "interpret" to do so before the tree is
even walked though :)

Ben.