linux-kernel - Re: [PATCH -next] net: hisilicon: Never build on SPARC

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Message-ID: <20151021215320.GB23371@roeck-us.net>
Date:	Wed, 21 Oct 2015 14:53:20 -0700
From:	Guenter Roeck <linux@...ck-us.net>
To:	Arnd Bergmann <arnd@...db.de>
Cc:	David Miller <davem@...emloft.net>, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH -next] net: hisilicon: Never build on SPARC

On Wed, Oct 21, 2015 at 09:11:53PM +0200, Arnd Bergmann wrote:
> On Wednesday 21 October 2015 10:03:05 Guenter Roeck wrote:
> > >
> > > Something like this?
> > >
> > > static inline u64 of_translate_address(struct device_node *np, const __be32 *addr)
> > > {
> > > #if defined(CONFIG_SPARC) || defined(CONFIG_M68K)
> > >       int pna = of_n_addr_cells(np);
> > >       u64 ret = be32_to_cpu(addr[pna - 1]);
> > >
> > >       if (pna > 1)
> > >               ret += (u64)be32_to_cpu(addr[pna - 2]) << 32;
> > >
> > >       return ret;
> > 
> > That suggests that sparc would need a translation after all, which
> > seems to contradict what David said earlier.
> 
> No, not a translation: the value is used without any offset that
> factors in the location of the bus, the above is just the shortest
> possible way to read the 64-bit number from a big-endian property
> of variable length.
> 
Out of my realm .. David would have to comment on that.

> > Anyway, if it gets that complicated, I think we should stick with
> > just returning OF_BAD_ADDR. The above really suggests the need for
> > an architecture specific solution.
> 
> Probably no harm in this really: the far more common
> of_address_to_resource() and of_iomap() helpers are equally
> broken on SPARC and we just return a runtime error for those
> as well without CONFIG_OF_ADDRESS rather than breaking the build.
> 
Agreed. Given this, returning OF_BAD_ADDR sounds like a better choice.

Thanks,
Guenter
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