Subject: Re: [RFC PATCH V1 14/33] powerpc/mm: Use helper for finding pte bits mapping I/O area

From: "Aneesh Kumar K.V" <[email-masked]>
Date: Wed, 13 Jan 2016 11:37:57 +0530

Benjamin Herrenschmidt <[email-masked]> 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 ?

-aneesh