lkml.org 
[lkml]   [2020]   [Jan]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [RFT 00/13] iomap: Constify ioreadX() iomem argument
From
Date


Le 08/01/2020 à 09:18, Krzysztof Kozlowski a écrit :
> On Wed, 8 Jan 2020 at 09:13, Geert Uytterhoeven <geert@linux-m68k.org> wrote:
>>
>> Hi Krzysztof,
>>
>> On Wed, Jan 8, 2020 at 9:07 AM Geert Uytterhoeven <geert@linux-m68k.org> wrote:
>>> On Tue, Jan 7, 2020 at 5:53 PM Krzysztof Kozlowski <krzk@kernel.org> wrote:
>>>> The ioread8/16/32() and others have inconsistent interface among the
>>>> architectures: some taking address as const, some not.
>>>>
>>>> It seems there is nothing really stopping all of them to take
>>>> pointer to const.
>>>
>>> Shouldn't all of them take const volatile __iomem pointers?
>>> It seems the "volatile" is missing from all but the implementations in
>>> include/asm-generic/io.h.
>>
>> As my "volatile" comment applies to iowrite*(), too, probably that should be
>> done in a separate patch.
>>
>> Hence with patches 1-5 squashed, and for patches 11-13:
>> Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
>
> I'll add to this one also changes to ioreadX_rep() and add another
> patch for volatile for reads and writes. I guess your review will be
> appreciated once more because of ioreadX_rep()
>

volatile should really only be used where deemed necessary:

https://www.kernel.org/doc/html/latest/process/volatile-considered-harmful.html

It is said: " ... accessor functions might use volatile on
architectures where direct I/O memory access does work. Essentially,
each accessor call becomes a little critical section on its own and
ensures that the access happens as expected by the programmer."

Christophe

\
 
 \ /
  Last update: 2020-01-08 09:37    [W:0.073 / U:58.860 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site