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Date:   Mon, 5 Sep 2022 08:49:58 -0700
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To:     Andy Shevchenko <andy.shevchenko@gmail.com>
Cc:     Dmitry Torokhov <dmitry.torokhov@gmail.com>,
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References: <20220903-gpiod_get_from_of_node-remove-v1-0-b29adfb27a6c@gmail.com>
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From:   Guenter Roeck <linux@roeck-us.net>
Subject: Re: [PATCH v1 10/11] watchdog: bd9576_wdt: switch to using
 devm_fwnode_gpiod_get()
In-Reply-To: <CAHp75VcisCTYoRp-=713YKtwi7BQyPKGiUhF4DkpfAFtvDXCiQ@mail.gmail.com>
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On 9/5/22 08:21, Andy Shevchenko wrote:
> On Mon, Sep 5, 2022 at 6:13 PM Guenter Roeck <linux@roeck-us.net> wrote:
>> On 9/5/22 04:09, Andy Shevchenko wrote:
>>> On Mon, Sep 5, 2022 at 9:33 AM Dmitry Torokhov
>>> <dmitry.torokhov@gmail.com> wrote:
> 
> ...
> 
>>>> +       count = device_property_count_u32(dev->parent, "rohm,hw-timeout-ms");
>>>> +       if (count < 0 && count != -EINVAL)
>>>> +               return count;
>>>> +
>>>> +       if (count > 0) {
>>>
>>>> +               if (count > ARRAY_SIZE(hw_margin))
>>>> +                       return -EINVAL;
>>>
>>> Why double check? You may move it out of the (count > 0).
>>
>> Two checks will always be needed, so I don't entirely see
>> how that would be better.
> 
> But not nested. That's my point:
> 
> if (count > ARRAY_SIZE())
>    return ...
> if (count > 0)
>    ...
> 

The old code has either 1 or two checks if there is no error.
Your suggested code has always two checks. I don't see how that
is an improvement.

>>>> -       if (ret == 1)
>>>> -               hw_margin_max = hw_margin[0];
>>>
>>>> +               ret = device_property_read_u32_array(dev->parent,
>>>> +                                                    "rohm,hw-timeout-ms",
>>>> +                                                    hw_margin, count);
>>>> +               if (ret < 0)
>>>> +                       return ret;
>>>
>>> So, only this needs the count > 0 check since below already has it implicitly.
>>>
>> Sorry, I don't understand this comment.
> 
> if (count > 0) {
>    ret = device_property_read_u32_array(...);
>    ...
> }
> if (count == 1)
>   ...
> if (count == 2)
>   ...
> 
> But here it might be better to have the nested conditionals.
> 

We know that count is either 1 or 2 here, so strictly speaking
	if (count == 1) {
	} else {
	}
would be sufficient. On the other side, that depends on ARRAY_SIZE() being
exactly 2, so
	if (count == 1) {
	} else if (count == 2) {
	}
would also make sense. Either way is fine with me. I'll leave it up
to Dmitry to decide what he wants to do.

Thanks,
Guenter

>>>> -       if (ret == 2) {
>>>> -               hw_margin_max = hw_margin[1];
>>>> -               hw_margin_min = hw_margin[0];
>>>> +               if (count == 1)
>>>> +                       hw_margin_max = hw_margin[0];
>>>> +
>>>> +               if (count == 2) {
>>>> +                       hw_margin_max = hw_margin[1];
>>>> +                       hw_margin_min = hw_margin[0];
>>>> +               }
>>>>           }
>