linux-kernel - Re: [PATCH v2 1/2] gpio: tps65219: add GPIO support for TPS65219 PMIC

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Date:   Fri, 12 May 2023 09:13:23 +0200
From:   jerome Neanne <jneanne@...libre.com>
To:     Linus Walleij <linus.walleij@...aro.org>
Cc:     Bartosz Golaszewski <brgl@...ev.pl>,
        Tony Lindgren <tony@...mide.com>, Lee Jones <lee@...nel.org>,
        linux-kernel@...r.kernel.org, linux-gpio@...r.kernel.org,
        linux-omap@...r.kernel.org,
        Jonathan Cormier <jcormier@...ticallink.com>
Subject: Re: [PATCH v2 1/2] gpio: tps65219: add GPIO support for TPS65219 PMIC



On 11/05/2023 22:57, Linus Walleij wrote:
>> +       /* Documentation is stating that GPIO0 direction must not be changed in Linux:
>> +        * Table 8-34. MFP_1_CONFIG(3): MULTI_DEVICE_ENABLE,
>> +        * Should only be changed in INITIALIZE state (prior to ON Request).
>> +        * Set statically by NVM, changing direction in application can cause a hang.
>> +        * Below can be used for test purpose only:
>> +        */
>> +
>> +#if 0
>> +       int ret = regmap_update_bits(gpio->tps->regmap, TPS65219_REG_MFP_1_CONFIG,
>> +                                TPS65219_GPIO0_DIR_MASK, direction);
>> +       if (ret)
>> +               return ret;
>> +#endif
>> +       dev_err(gpio->tps->dev,
>> +               "GPIO%d direction set by NVM, change to %u failed, not allowed by specification\n",
>> +                offset, direction);
>> +       return -EOPNOTSUPP;
>> +}
> 
> Normally people would complain about #if 0 code.
> 
> But this is a special case!
> 
> I definitely want the code to be in there somehow.
> 
> What about:
> 
> if (IS_ENABLED(DEBUG))?
> 
> If someone enables debug with an explicit -DDEBUG to the compiler
> this could be allowed.
I'm fine with your proposal. Will wait few days just in case anyone 
wants to add any comment then go for this.