Re: [PATCH v2 3/3] gpio: Add Spreadtrum PMIC EIC driver support

[Baolin Wang]

On 27 February 2018 at 23:54, Andy Shevchenko <andy.shevchenko@xxxxxxxxx> wrote:
> On Tue, Feb 27, 2018 at 4:35 AM, Baolin Wang <baolin.wang@xxxxxxxxxx> wrote:
>> On 26 February 2018 at 20:02, Andy Shevchenko <andy.shevchenko@xxxxxxxxx> wrote:
>>> On Mon, Feb 26, 2018 at 5:01 AM, Baolin Wang <baolin.wang@xxxxxxxxxx> wrote:
>>>> On 25 February 2018 at 20:19, Andy Shevchenko <andy.shevchenko@xxxxxxxxx> wrote:
>
>>>>>> +       for (n = 0; n < chip->ngpio; n++) {
>>>>>> +               if (!(BIT(n) & val))
>>>>>
>>>>> for_each_set_bit().
>>>>>
>>>>> At some point you may need just to go across lib/ in the kernel and
>>>>> see what we have there.
>>>>
>>>> I've considered the for_each_set_bit(), it need one 'unsigned long'
>>>> type parameter, but we get the value from regmap is 'u32' type. So we
>>>> need one extra conversion from 'u32' to 'unsigned long' like:
>>>>
>>>> unsigned long reg = val;
>>>>
>>>> for_each_set_bit(n, &reg, chip->ngpio) {
>>>>         .......
>>>> }
>>>>
>>>> If you like this conversion, then I can change to use
>>>> for_each_set_bit(). Thanks.
>>>
>>> Wouldn't it work like
>>>
>>> unsigned long val;
>>>
>>> ...regmap_read(..., &val);
>>>
>>> ?
>>
>> It can not work, regmap_read() expects 'unsigned int *'.
>
> Ah, OK, than the temporary variable is a left approach.
>
>> But I can
>> convert it like this:
>>
>> for_each_set_bit(n, (unsigned long *)&val, chip->ngpio) {
>>          .......
>> }
>
> No, this is a boilerplate for static analyzers and definitely UB.

OK. Thanks for pointing this issue out.

-- 
Baolin.wang
Best Regards