Re: [PATCH v2 01/10] arch: introduce __pfn_t for persistent memory i/o

[Dan Williams]

On Thu, May 7, 2015 at 7:55 AM, Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx> wrote:
> Hi Dan,
>
> On Wed, 06 May 2015 16:04:59 -0400 Dan Williams <dan.j.williams@xxxxxxxxx> wrote:
>>
>> diff --git a/include/asm-generic/pfn.h b/include/asm-generic/pfn.h
>> new file mode 100644
>> index 000000000000..91171e0285d9
>> --- /dev/null
>> +++ b/include/asm-generic/pfn.h
>> @@ -0,0 +1,51 @@
>> +#ifndef __ASM_PFN_H
>> +#define __ASM_PFN_H
>> +
>> +#ifndef __pfn_to_phys
>> +#define __pfn_to_phys(pfn)      ((dma_addr_t)(pfn) << PAGE_SHIFT)
>
> Why dma_addr_t and not phys_addr_t?  i.e. it could use a comment if it
> is correct.

Hmm, this was derived from:

#define page_to_phys(page)    ((dma_addr_t)page_to_pfn(page) << PAGE_SHIFT)

in arch/x86/include/asm/io.h

The primary users of __pfn_to_phys() is dma_map_page().  I'll add a
comment to that effect.
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