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Message-ID: <1452669487.2403.25.camel@kernel.crashing.org>
Subject: Re: [RFC PATCH V1 14/33] powerpc/mm: Use helper for finding pte
 bits mapping I/O area
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>, Denis Kirjanov
 <kda@linux-powerpc.org>
Cc: paulus@samba.org, mpe@ellerman.id.au, Michael Neuling <mikey@neuling.org>,
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Date: Wed, 13 Jan 2016 18:18:07 +1100
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On Wed, 2016-01-13 at 11:37 +0530, Aneesh Kumar K.V wrote:
> Benjamin Herrenschmidt <benh@kernel.crashing.org> writes:
> 
> > On Tue, 2016-01-12 at 10:42 +0300, Denis Kirjanov wrote:
> > > > +static inline unsigned long pte_io_cache_bits(void)
> > > > +{
> > > > +     return _PAGE_NO_CACHE | _PAGE_GUARDED;
> > > > +}
> > > This could be just plain #define
> > 
> > Or just use pgprot_noncached()
> > 
> #define pgprot_noncached(prot)	  (__pgprot((pgprot_val(prot) &
> ~_PAGE_CACHE_CTL) | \
> 				            _PAGE_NO_CACHE |
> _PAGE_GUARDED))
> 
> 
> That will return me a pgprot_t.  I can fix that by using
> pgprot_val(pgprot_noncached(0)). Is that what you are suggesting ?

Shouln't ioremap just use pgprot_noncached(PAGE_KERNEL) or similar ?

Cheers,
Ben.