Re: [PATCH v5 3/6] iomap: introduce io{read|write}64_{lo_hi|hi_lo}

[Andy Shevchenko]

On Mon, Jul 31, 2017 at 7:31 PM, Logan Gunthorpe <logang@xxxxxxxxxxxx> wrote:
> On 31/07/17 10:10 AM, Andy Shevchenko wrote:
>> Some drivers (hardware) would like to have non-atomic MMIO accesses
>> when readq() defined
>
> Huh? But that's the whole point of the io64-nonatomic header. If a
> driver wants a specific non-atomic access they should just code two 32
> bit accesses.

You mean to call them directly as lo_hi_XXX() or hi_lo_XXX() ?
Yes it would work.

>> In case of readq() / writeq() it's defined by the order of inclusion:
>>
>> 1)
>> include <...non-atomic...>
>> include <linux/io.h>
>>
>> Always non-atomic will be used.
>
> I'm afraid you're wrong about this. The io-64-nonatomic-xx header
> includes linux/io.h. Thus the order of the includes doesn't matter and
> it will always auto switch. In any case, making an interface do
> different things depending on the order of include files is *completely*
> insane.

Yes, you are right. I was thinking about something unrelated.

-- 
With Best Regards,
Andy Shevchenko