linux-kernel - Re: [PATCH v4 4/4] iio: adc: mcp3911: add support for the whole MCP39xx family

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Message-ID: <3939bd56-d57d-173e-da78-297ce607f9bc@linaro.org>
Date:   Wed, 9 Aug 2023 20:14:54 +0200
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Jonathan Cameron <jic23@...nel.org>,
        Marcus Folkesson <marcus.folkesson@...il.com>
Cc:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Kent Gustavsson <kent@...oris.se>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Cosmin Tanislav <demonsingur@...il.com>,
        Arnd Bergmann <arnd@...db.de>,
        ChiYuan Huang <cy_huang@...htek.com>,
        Haibo Chen <haibo.chen@....com>,
        Ramona Bolboaca <ramona.bolboaca@...log.com>,
        Ibrahim Tilki <Ibrahim.Tilki@...log.com>,
        ChiaEn Wu <chiaen_wu@...htek.com>,
        William Breathitt Gray <william.gray@...aro.org>,
        linux-iio@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 4/4] iio: adc: mcp3911: add support for the whole
 MCP39xx family

On 09/08/2023 20:02, Jonathan Cameron wrote:
> On Wed, 9 Aug 2023 08:41:05 +0200
> Marcus Folkesson <marcus.folkesson@...il.com> wrote:
> 
>>> ...
>>>   
>>>> +#define MCP3910_OFFCAL(x)		(MCP3910_REG_OFFCAL_CH0 + x * 6)  
>>>
>>> Inconsistent macro implementation, i.e. you need to use (x).  
>>
>> Sorry, I do not get you
>>
>>
>> [...]
>>
>>>> +static int mcp3910_get_osr(struct mcp3911 *adc, int *val)
>>>> +{
>>>> +	int ret, osr;  
>>>
>>> Strictly speaking osr can't be negative, otherwise it's a UB below.
>>>
>>> 	u32 osr = FIELD_GET(MCP3910_CONFIG0_OSR, *val);
>>> 	int ret;
>>>
>>> and why val is int?  
>>
>> I will change val to u32 for *_get_osr(), *_set_osr() and *_set_scale().
>>
>> [...]
>>
>>>> +	if (device_property_read_bool(&adc->spi->dev, "microchip,data-ready-hiz"))  
>>>
>>> This also becomes shorter.
>>>
>>> One trick to make it even shorter:
>>>
>>> 	if (device_property_present(dev, "microchip,data-ready-hiz"))  
>>
>> Thank you, I wasn't aware of device_property_present().
> 
> I know the read_bool function is direct equivalent of this but where a property
> is a flag, it feels more natural to me to check it with that one.
> read_present() feels more appropriate for where you want to know a more
> complex property is present.
> 
> Doesn't matter that much either way however so up to you.

For the OF, of_property_read_bool() is indeed preferred. Is there
device-xxx() equivalent?

Best regards,
Krzysztof