linux-kernel - Re: [PATCH] of/base: Fix PowerPC address parsing hack

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Date:	Wed, 12 Nov 2014 08:39:32 -0600
From:	Rob Herring <robherring2@...il.com>
To:	Benjamin Herrenschmidt <benh@...nel.crashing.org>
Cc:	Grant Likely <grant.likely@...aro.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Arnd Bergmann <arnd@...db.de>, Olof Johansson <olof@...om.net>,
	linuxppc-dev <linuxppc-dev@...abs.org>
Subject: Re: [PATCH] of/base: Fix PowerPC address parsing hack

On Tue, Nov 11, 2014 at 11:51 PM, Benjamin Herrenschmidt
<benh@...nel.crashing.org> 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 <benh@...nel.crashing.org>
> CC: <stable@...r.kernel.org>
> ---
>
> 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.

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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