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

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Message-ID: <8f588f4b88d122815df694660d19672e8ccd3d70.camel@gmail.com>
Date: Thu, 20 Feb 2025 14:53:52 +0000
From: Nuno Sá <noname.nuno@...il.com>
To: Antoniu Miclaus <antoniu.miclaus@...log.com>, jic23@...nel.org, 
	robh@...nel.org, conor+dt@...nel.org, linux-iio@...r.kernel.org, 
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 14/14] Documentation: ABI: testing: ad4080 docs

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@...log.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@...r.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@...r.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@...r.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@...r.kernel.org
> +Description:
> +		Return the available filter modes that can be set.

There's a standard attr for this. I think we settled 
> +
> +What:		/sys/bus/iio/devices/iio:deviceX/sinc_dec_rate
> +Date:		February 2025
> +KernelVersion:
> +Contact:	linux-iio@...r.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@...r.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.

- Nuno Sá