From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Grant Likely <grant.likely@linaro.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>,
Rob Herring <robherring2@gmail.com>,
Olof Johansson <olof@lixom.net>,
"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Arnd Bergmann <arnd@arndb.de>,
linuxppc-dev <linuxppc-dev@ozlabs.org>
Subject: Re: [PATCH] of/base: Fix PowerPC address parsing hack
Date: Thu, 13 Nov 2014 23:53:47 +1100 [thread overview]
Message-ID: <1415883227.666.6.camel@kernel.crashing.org> (raw)
In-Reply-To: <CACxGe6s0CXL2oRKCLhzzycOKWJStxdZsc1pn_X8fLuAqCguBMA@mail.gmail.com>
On Thu, 2014-11-13 at 12:44 +0000, Grant Likely wrote:
> On Thu, Nov 13, 2014 at 12:45 AM, Benjamin Herrenschmidt
> <benh@kernel.crashing.org> wrote:
> > What about this one instead ? I want to cache it because that function
> > can be called quite a while and doing two additional property lookup
> > and string compares every time might hurt some platforms.
> >
> > ----
> >
> > 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@kernel.crashing.org>
> > CC: <stable@vger.kernel.org>
>
> How far back does this need to go? I assume I need to get this in for v3.18.
I'd like some distro to pick it up in 3.16
> > diff --git a/drivers/of/address.c b/drivers/of/address.c
> > index e371825..5eae0cd 100644
> > --- a/drivers/of/address.c
> > +++ b/drivers/of/address.c
> > @@ -403,6 +403,17 @@ static struct of_bus *of_match_bus(struct device_node *np)
> > return NULL;
> > }
> >
> > +static int of_empty_ranges_quirk(void)
> > +{
> > + /* To save cycles, we cache the result */
> > + static int quirk_state = -1;
> > +
>
> if (IS_ENABLED(CONFIG_POWERPC)) {
>
> > + if (quirk_state < 0)
> > + quirk_state = of_machine_is_compatible("Power Macintosh") ||
> > + of_machine_is_compatible("MacRISC");
> > + return quirk_state;
>
> }
> return 0;
>
> So it gets compiled out for non powerpc.
Yeah, I'm set in my ways, keep forgetting about all the shiny new stuff.
> > +}
> > +
> > static int of_translate_one(struct device_node *parent, struct of_bus *bus,
> > struct of_bus *pbus, __be32 *addr,
> > int na, int ns, int pna, const char *rprop)
> > @@ -428,12 +439,10 @@ 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 (ranges == NULL) {
> > + if (ranges == NULL && !of_empty_ranges_quirk()) {
> > pr_err("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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next prev parent reply other threads:[~2014-11-13 12:54 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-11-12 5:51 [PATCH] of/base: Fix PowerPC address parsing hack Benjamin Herrenschmidt
2014-11-12 14:39 ` Rob Herring
2014-11-12 17:02 ` Grant Likely
2014-11-12 19:55 ` Benjamin Herrenschmidt
2014-11-12 22:10 ` Stephen Rothwell
2014-11-12 23:08 ` Benjamin Herrenschmidt
2014-11-13 0:45 ` Benjamin Herrenschmidt
2014-11-13 1:02 ` Stephen Rothwell
2014-11-13 12:44 ` Grant Likely
2014-11-13 12:53 ` Benjamin Herrenschmidt [this message]
2014-11-14 6:55 ` [PATCH v3] " Benjamin Herrenschmidt
2014-11-18 16:52 ` Grant Likely
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