Re: [PATCH] coccinelle: api: detect unnecessary le16_to_cpu

From: Andy Shevchenko
Date: Mon Jul 03 2017 - 13:34:02 EST


On Mon, Jul 3, 2017 at 8:14 PM, Sebastian Reichel
<sebastian.reichel@xxxxxxxxxxxxxxx> wrote:
> Hi,
>
> On Mon, Jul 03, 2017 at 07:37:59PM +0300, Andy Shevchenko wrote:
>> On Mon, Jul 3, 2017 at 4:36 PM, Sebastian Reichel
>> <sebastian.reichel@xxxxxxxxxxxxxxx> wrote:
>> > On Sat, Jul 01, 2017 at 09:28:10PM +0200, Julia Lawall wrote:
>>
>> > * drivers/gpio/gpio-pca953x.c (line 190-192)
>>
>> It has double conversion there:
>> 1. LE CPU: Read as LE and converted to LE (no-op), so, just u16
>> 2. BE CPU: Read as BE and converted to LE, makes it __le16
>>
>> Looks like the conversion is not needed, only get_unaligned() is necessary.
>>
>> P.S. What about lines 244-245 there? I think they are no-op.
>> Interesting that those two parts were added in quite different
>> commits.
>
> val[0] = (u16)ret & 0xFF;
> val[1] = (u16)ret >> 8;
>
> looks like cpu_to_be16()?

cpu_to_le16(). No-op on LE CPU.

Perhaps they should be replaced by put_unaligned().

--
With Best Regards,
Andy Shevchenko