RE: [PATCH v3 2/3] iio:adc:imx: add Freescale Vybrid vf610 adc driver

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From: Lars-Peter Clausen [mailto:lars@xxxxxxxxxx]
Data: Wednesday, November 27, 2013 4:21 PM

>To: Duan Fugang-B38611
>Cc: jic23@xxxxxxxxxx; sachin.kamat@xxxxxxxxxx; devicetree@xxxxxxxxxxxxxxx;
>shawn.guo@xxxxxxxxxx; Li Frank-B20596; linux-iio@xxxxxxxxxxxxxxx
>Subject: Re: [PATCH v3 2/3] iio:adc:imx: add Freescale Vybrid vf610 adc driver
>
>On 11/27/2013 05:44 AM, Fugang Duan wrote:
>[...]
>>>> +	if (info->vref)
>>>> +		info->vref_uv = regulator_get_voltage(info->vref);
>>>> +	else if (of_property_read_u32(np, "fsl,adc-vref", &info->vref_uv))
>>>> +		dev_err(info->dev,
>>>> +			"Miss adc-vref property or vref regulator in the DT.\n");
>>>
>>> If you have a fixed reference voltage use the fixed voltage
>>> regulator. Don't invent custom ways of specifying this.
>>>
>> Different boards design may use different method to supply the reference
>voltage.
>> There maybe fixed voltage regulator, maybe no regulator just use fixed
>voltage.
>
>Well the voltage has to come from somewhere and that source should be described
>in the DT with a fixed regulator.
>

Good suggestion. Thanks.

>>
>>>> +
>>>> +	if (of_property_read_u32(np, "fsl,adc-clk-div",
>>>> +			&info->adc_feature.clk_div_num)) {
>>>> +		info->adc_feature.clk_div_num = 2;
>>>> +		dev_info(info->dev,
>>>> +			"Miss adc-clk-div in dt, set divider to 2.\n");
>>>> +	}
>>>> +
>>>> +	if (of_property_read_u32(np, "fsl,adc-res",
>>>> +			&info->adc_feature.res_mode)) {
>>>> +		info->adc_feature.res_mode = 12;
>>>> +		dev_info(info->dev,
>>>> +			"Miss adc-res property in dt, use 8bit mode.\n");
>>>> +	}
>>>> +
>>>> +	if (of_property_read_u32(np, "fsl,adc-sam-time",
>>>> +			&info->adc_feature.sam_time)) {
>>>> +		info->adc_feature.sam_time = 4;
>>>> +		dev_info(info->dev,
>>>> +			"Miss adc-sam-time property in dt, set to 4.\n");
>>>> +	}
>>>> +
>>>> +	info->adc_feature.hw_average = of_property_read_bool(np,
>>>> +					"fsl,adc-hw-aver-en");
>>>> +	if (info->adc_feature.hw_average &&
>>>> +		 of_property_read_u32(np, "fsl,adc-aver-sam-sel",
>>>> +				&info->adc_feature.hw_sam)) {
>>>> +		info->adc_feature.hw_sam = 4;
>>>> +		dev_info(info->dev,
>>>> +			"Miss adc-aver-sam-sel property in dt, set to 4.\n");
>>>> +	}
>>>> +
>>>> +	info->adc_feature.lpm = of_property_read_bool(np,
>>>> +"fsl,adc-low-power-
>>> mode");
>>>> +	info->adc_feature.hs_oper = of_property_read_bool(np,
>>>> +"fsl,adc-high-speed-conv");
>>>
>>> Some of the properties look like they should be runtime configurable
>>> rather then board specific settings. E.g. the resolution or the
>>> sampling frequency, or whether averaging is enabled.
>>>
>>>
>> So, I have question:
>> Since the ADC have many user configurable setting, I have import some of them
>from DT, and some of them use static define.
>> How to set/change them in runtime for user configuration ?
>> Introduce ioctl ?
>
>I think a lot of them already map to standard iio properties. E.g. the
>samplerate. So you'd expose them as sysfs attributes. But please use standard
>attributes here instead of inventing your own with cryptic names.
>
>- Lars

Good suggestion, I will use the standard IIO interface for the ADC configuration.

Thanks,
Andy

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