Re: [PATCH 14/14] Documentation: ABI: testing: ad4080 docs

[David Lechner <dlechner@baylibre.com>]

On 2/20/25 8:53 AM, Nuno Sá wrote:
> On Thu, 2025-02-20 at 15:54 +0200, Antoniu Miclaus wrote:
>> Add documentation for the ad4080 attributes.
>>
>> Signed-off-by: Antoniu Miclaus <antoniu.miclaus@analog.com>
>> ---
>>  .../ABI/testing/sysfs-bus-iio-adc-ad4080      | 55 +++++++++++++++++++
>>  1 file changed, 55 insertions(+)
>>  create mode 100644 Documentation/ABI/testing/sysfs-bus-iio-adc-ad4080
>>
>> diff --git a/Documentation/ABI/testing/sysfs-bus-iio-adc-ad4080
>> b/Documentation/ABI/testing/sysfs-bus-iio-adc-ad4080
>> new file mode 100644
>> index 000000000000..e37bfba0e989
>> --- /dev/null
>> +++ b/Documentation/ABI/testing/sysfs-bus-iio-adc-ad4080
>> @@ -0,0 +1,55 @@
>> +What:		/sys/bus/iio/devices/iio:deviceX/lvds_sync
>> +Date:		February 2025
>> +KernelVersion:
>> +Contact:	linux-iio@vger.kernel.org
>> +Description:
>> +		This attribute handles the data synchronization
>> process.Because the CNV
>> +		signal is not taken into account by the FPGA when capturing
>> the data, we
>> +		need a process that configures the ADC to output pattern
>> data, writes the
>> +		SYNC bit in the axi_adc register map, waits until the custom
>> HDL syncs the
>> +		data correctly, and then changes the output mode to analog
>> data instead of
>> +		the fixed pattern.
> 
> I'll comment this one in the driver. I have some questions on how this works...
> 
>> +
>> +What:		/sys/bus/iio/devices/iio:deviceX/lvds_lvds
>> +Date:		February 2025
>> +KernelVersion:
>> +Contact:	linux-iio@vger.kernel.org
>> +Description:
>> +		Configures the signal type of the CNV signal. The value can
>> be either CMOS
>> +		(lvds_cnv=0) or LVDS (lvds_cnv=1).
> 
> The name seems to be wrong with what you have implemented. From this
> description, I would think of this as a DT property? Can the signal type really
> change at runtime?
> 
>> +
>> +What:		/sys/bus/iio/devices/iio:deviceX/filter_sel
>> +Date:		February 2025
>> +KernelVersion:
>> +Contact:	linux-iio@vger.kernel.org
>> +Description:
>> +		This attribute enables the digital filter functionality of
>> the AD4080.In
>> +		order to capture data correctly, the function must configure
>> the ADC
>> +		through SPI to select the filter type and enable data capture
>> in filter
>> +		mode through axi_adc(In this mode, data is gated by a signal
>> generated by
>> +		the AD4080 (GPIO1 and is not continuous as it is when the
>> filter is
>> +		disabled).
>> +
>> +What:		/sys/bus/iio/devices/iio:deviceX/filter_sel_available
>> +Date:		February 2025
>> +KernelVersion:
>> +Contact:	linux-iio@vger.kernel.org
>> +Description:
>> +		Return the available filter modes that can be set.
> 
> There's a standard attr for this. I think we settled 

Yup. filter_type and filter_type_available. 

>> +
>> +What:		/sys/bus/iio/devices/iio:deviceX/sinc_dec_rate
>> +Date:		February 2025
>> +KernelVersion:
>> +Contact:	linux-iio@vger.kernel.org
>> +Description:
>> +		Set the filter’s decimation rate.
>> +
>> +What:		/sys/bus/iio/devices/iio:deviceX/sinc_dec_rate_available
>> +Date:		February 2025
>> +KernelVersion:
>> +Contact:	linux-iio@vger.kernel.org
>> +Description:
>> +		Return the available filter's decimation rates.
>> +
>> +
> 
> I'm not yet convinced we need the dec_rate custom attr. I'll add more comments
> in the driver.

If we do need it, in another driver recently we concluded that
decimation rate is the same as oversampling ratio and there is
already a standard attribute for oversampling ratio, so we used
that.

> 
> - Nuno Sá
> 
>