linux-kernel - Re: [PATCH v1 10/11] watchdog: bd9576_wdt: switch to using devm_fwnode_gpiod

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Message-ID: <c696b9bf-d0ce-1c6a-0ee3-939b180891be@roeck-us.net>
Date:   Mon, 5 Sep 2022 08:49:58 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Thierry Reding <thierry.reding@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Matti Vaittinen <mazziesaccount@...il.com>,
        Lorenzo Pieralisi <lpieralisi@...nel.org>,
        Claudiu Beznea <claudiu.beznea@...rochip.com>,
        Liam Girdwood <lgirdwood@...il.com>,
        Wim Van Sebroeck <wim@...ux-watchdog.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Miquel Raynal <miquel.raynal@...tlin.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Felipe Balbi <balbi@...nel.org>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        Krzysztof Wilczyński <kw@...ux.com>,
        Vignesh Raghavendra <vigneshr@...com>,
        Daniel Vetter <daniel@...ll.ch>,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
        Alexandre Torgue <alexandre.torgue@...s.st.com>,
        Marc Zyngier <maz@...nel.org>,
        Richard Weinberger <richard@....at>,
        David Airlie <airlied@...ux.ie>,
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        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Pali Rohár <pali@...nel.org>,
        LINUXWATCHDOG <linux-watchdog@...r.kernel.org>,
        USB <linux-usb@...r.kernel.org>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
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        linux-arm Mailing List <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v1 10/11] watchdog: bd9576_wdt: switch to using
 devm_fwnode_gpiod_get()

On 9/5/22 08:21, Andy Shevchenko wrote:
> On Mon, Sep 5, 2022 at 6:13 PM Guenter Roeck <linux@...ck-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@...il.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];
>>>> +               }
>>>>           }
>