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

From: Logan Gunthorpe
Date: Mon Jul 31 2017 - 14:00:42 EST




On 31/07/17 11:58 AM, Andy Shevchenko wrote:
> 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.

I suppose you could do that too but I really meant just using two io32
calls. That's the most explicit way to indicate you want a non-atomic
access.

Logan