linux-kernel - Re: [PATCH v2 1/5] Documentation: ABI: add oversampling frequency in sysfs-bus-iio

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Message-ID: <c3i7g273lgvx7rpihzq6r7exxxnglbwrqwfryyz6ciqo52tszf@cvi7pz4bmkvq>
Date: Tue, 29 Apr 2025 15:47:05 +0200
From: Jorge Marques <gastmaier@...il.com>
To: Andy Shevchenko <andy@...nel.org>
Cc: Jorge Marques <jorge.marques@...log.com>, 
	Jonathan Cameron <jic23@...nel.org>, Lars-Peter Clausen <lars@...afoo.de>, 
	Michael Hennerich <Michael.Hennerich@...log.com>, Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Jonathan Corbet <corbet@....net>, David Lechner <dlechner@...libre.com>, 
	Nuno Sá <nuno.sa@...log.com>, Uwe Kleine-König <ukleinek@...nel.org>, 
	linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org, devicetree@...r.kernel.org, 
	linux-doc@...r.kernel.org, linux-pwm@...r.kernel.org
Subject: Re: [PATCH v2 1/5] Documentation: ABI: add oversampling frequency in
 sysfs-bus-iio


Hi Andy,

I agree with your suggestion, and in this case the appropriate kernel
version is 3.10.

On Tue, Apr 22, 2025 at 06:50:19PM +0300, Andy Shevchenko wrote:
> On Tue, Apr 22, 2025 at 01:34:46PM +0200, Jorge Marques wrote:
> > Some devices have an internal clock used to space out the conversion
> > trigger for the oversampling filter,
> > Consider an ADC with conversion and data ready pins topology:
> > 
> >   Sampling trigger |       |       |       |       |
> >   ADC conversion   ++++    ++++    ++++    ++++    ++++
> >   ADC data ready      *       *       *       *       *
> > 
> > With the oversampling frequency, conversions are spaced:
> > 
> >   Sampling trigger |       |       |       |       |
> >   ADC conversion   + + + + + + + + + + + + + + + + + + + +
> >   ADC data ready         *       *       *       *       *
> > 
> > In some devices and ranges, this internal clock can be used to evenly
> > space the conversions between the sampling edge.
> > In other devices the oversampling frequency is fixed or is computed
> > based on the sampling frequency parameter, and the parameter is
> > read only.
> > 
> > Devices with this feature are max1363, ad7606, ad799x, and ad4052.
> > The max1363 driver included the events/sampling_frequency in
> > commit 168c9d95a940 ("iio:adc:max1363 move from staging.")
> > and ad799x in
> > commit ba1d79613df3 ("staging:iio:ad799x: Use event spec for threshold
> > hysteresis")
> > but went undocumented so far.
> 
> So, it was no documentation for the nodes this change describes, right?
> 
> ...
> 
> > +What:		/sys/bus/iio/devices/iio:deviceX/oversampling_frequency
> > +KernelVersion:	6.15
> 
> Then why don't you put the real version of the first release that has it?
> 
> > +Contact:	linux-iio@...r.kernel.org
> > +Description:
> > +		Some devices have internal clocks for oversampling.
> > +		Sets the resulting frequency in Hz to trigger a conversion used by
> > +		the oversampling filter.
> > +		If the device has a fixed internal clock or is computed based on
> > +		the sampling frequency parameter, the parameter is read only.
> > +
> > +What:		/sys/bus/iio/devices/iio:deviceX/oversampling_frequency_available
> > +KernelVersion:	6.15
> 
> Ditto.
> 
> > +Contact:	linux-iio@...r.kernel.org
> > +Description:
> > +		Hardware dependent values supported by the oversampling
> > +		frequency.
> 
> -- 
> With Best Regards,
> Andy Shevchenko
> 

Best regards,
Jorge