Subject: Re: [PATCH] of/base: Fix PowerPC address parsing hack

From: Benjamin Herrenschmidt <[email-masked]>
Date: Thu, 13 Nov 2014 06:55:07 +1100

On Wed, 2014-11-12 at 08:39 -0600, Rob Herring wrote:
> On Tue, Nov 11, 2014 at 11:51 PM, Benjamin Herrenschmidt
> <[email-masked]> wrote:
> > We have a historical hack that treats missing ranges properties as the
> > equivalent of an empty one. This is needed for ancient PowerMac "bad"
> > device-trees, and shouldn't be enabled for any other PowerPC platform,
> > otherwise we get some nasty layout of devices in sysfs or even
> > duplication when a set of otherwise identically named devices is
> > created multiple times under a different parent node with no ranges
> > property.
> >
> > This fix is needed for the PowerNV i2c busses to be exposed properly
> > and will fix a number of other embedded cases.
> >
> > Signed-off-by: Benjamin Herrenschmidt <[email-masked]>
> > CC: <[email-masked]>
> > ---
> >
> > diff --git a/drivers/of/address.c b/drivers/of/address.c
> > index e371825..e37f017 100644
> > --- a/drivers/of/address.c
> > +++ b/drivers/of/address.c
> > @@ -7,6 +7,10 @@
> >  #include <linux/pci_regs.h>
> >  #include <linux/string.h>
> >
> > +#ifdef CONFIG_PPC
> > +#include <asm/machdep.h>
> > +#endif
> > +
> >  /* Max address size we deal with */
> >  #define OF_MAX_ADDR_CELLS      4
> >  #define OF_CHECK_ADDR_COUNT(na)        ((na) > 0 && (na) <= OF_MAX_ADDR_CELLS)
> > @@ -428,12 +432,13 @@ static int of_translate_one(struct device_node *parent, struct of_bus *bus,
> >          * This code is only enabled on powerpc. --gcl
> >          */
> >         ranges = of_get_property(parent, rprop, &rlen);
> > -#if !defined(CONFIG_PPC)
> > +#if defined(CONFIG_PPC)
> > +       if (!machine_is(powermac))
> 
> Can we use a machine compatible here or something not PPC specific?
> Then we can use IS_ENABLED(CONFIG_PPC) instead of ifdefs.

We could, we'd have to use a pair of machine compatible, I'll spin a new
patch later today.

Ben.
 
> Rob
> 
> > +#endif /* defined(CONFIG_PPC) */
> >         if (ranges == NULL) {
> > -               pr_err("OF: no ranges; cannot translate\n");
> > +               pr_debug("OF: no ranges; cannot translate\n");
> >                 return 1;
> >         }
> > -#endif /* !defined(CONFIG_PPC) */
> >         if (ranges == NULL || rlen == 0) {
> >                 offset = of_read_number(addr, na);
> >                 memset(addr, 0, pna * 4);
> >
> --
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