linux-kernel - Re: [PATCH v3] iio: adc: Add support for TI ADC108S102 and ADC128S102

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Fri, 5 May 2017 12:39:01 +0200
From:   Jan Kiszka <jan.kiszka@...mens.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Jonathan Cameron <jic23@...nel.org>
Cc:     linux-iio@...r.kernel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Sascha Weisenberger <sascha.weisenberger@...mens.com>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>,
        Rob Herring <robh@...nel.org>
Subject: Re: [PATCH v3] iio: adc: Add support for TI ADC108S102 and ADC128S102

On 2017-05-05 11:54, Andy Shevchenko wrote:
> On Fri, 2017-05-05 at 08:31 +0200, Jan Kiszka wrote:
>> This is an upstream port of an IIO driver for the TI ADC108S102 and
>> ADC128S102. The former can be found on the Intel Galileo Gen2 and the
>> Siemens SIMATIC IOT2000. For those boards, ACPI-based enumeration is
>> included.
>>
>> Due to the lack of regulators under ACPI, we need a special device
>> property to define the voltage provide to the VA pin of the ADC
>> ("va-millivolt"). For DT usage, the regulator "vref-supply" is
>> requested. Note that DT usage has not been tested.
> 
> +1 to what Mika commented on this and just some additional information.
> 
> Other than that looks pretty good.
> 
>> Changes in v3:
>>  - Reworked reference voltage handling, splitting up the different
>> ACPI
>>    case from DT usage. This also means that the "va-millivolt"
>>    (formerly and incorrectly called "ext-vin-microvolt") becomes
>>    ACPI-only
> 
> Just to be clean, there is *no* such thing as *XYZ-only* device
> properties. The idea behind them is to provide resource provider
> agnostic API to read properties.

Well, as along as ACPI does its own thing /wrt regulators, we have that
problem. But let's wait until someone designs an ACPI board with that
chip and a different reference voltage.

> 
>> +			if (st->reg)
>> +				*val = regulator_get_voltage(st->reg) 
>> / 1000;
>> +			else
>> +				*val = st->va_millivolt;
>> +
> 
> Another way is to not just hard code the value, but create a fixed
> voltage regulator out of it. In this case you will have one way to get
> its value.

That's a good idea.

> 
>> +		st->reg = devm_regulator_get(&spi->dev, "vref");
> 
> It should be _optional like I mentioned in one of previous review.
> 
>> +	if (!IS_ERR(st->reg))
> 
> This is redundant

It's not for the existing code because regulator_disable doesn't test
this for us. It will be, though, when I switch back to making it
mandatory for everyone.

Jan

> 
>> +		regulator_disable(st->reg);
> 
>> +	if (!IS_ERR(st->reg))
> 
> Ditto.
> 
>> +		regulator_disable(st->reg);
> 
> 

-- 
Siemens AG, Corporate Technology, CT RDA ITP SES-DE
Corporate Competence Center Embedded Linux