linux-kernel - Re: [PATCH 2/2] doc: iio: ad4695: document buffered read

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Message-ID: <20240810103630.0fbe8610@jic23-huawei>
Date: Sat, 10 Aug 2024 10:36:30 +0100
From: Jonathan Cameron <jic23@...nel.org>
To: David Lechner <dlechner@...libre.com>
Cc: Michael Hennerich <Michael.Hennerich@...log.com>, Nuno Sá
 <nuno.sa@...log.com>, Jonathan Corbet <corbet@....net>,
 linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-doc@...r.kernel.org
Subject: Re: [PATCH 2/2] doc: iio: ad4695: document buffered read

On Wed,  7 Aug 2024 15:02:11 -0500
David Lechner <dlechner@...libre.com> wrote:

> The ad4695 driver has a quirk where the temperature channel can't be
> enabled on its own for buffered reads, so we should document this.
> 
> Also, since there are 4 possible modes of reading conversion data, it
> is useful to know which one is actually being used, namely the advanced
> sequencer mode.
> 
> Signed-off-by: David Lechner <dlechner@...libre.com>
> ---
>  Documentation/iio/ad4695.rst | 12 +++++++++++-
>  1 file changed, 11 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/iio/ad4695.rst b/Documentation/iio/ad4695.rst
> index a33e573d61d6..af76ce2d0702 100644
> --- a/Documentation/iio/ad4695.rst
> +++ b/Documentation/iio/ad4695.rst
> @@ -147,9 +147,19 @@ Unimplemented features
>  ----------------------
>  
>  - Additional wiring modes
> -- Buffered reads
>  - Threshold events
>  - Oversampling
>  - Gain/offset calibration
>  - GPIO support
>  - CRC support
> +
> +Device buffers
> +==============
> +
> +This driver supports hardware triggered buffers. This uses the "advanced
> +sequencer" feature of the chip to trigger a burst of conversions.
> +
> +Due to hardware constraints, the temperature channel cannot be read on its own
> +for buffered reads. At least one voltage channel must also be enabled.
As per driver review, userspace shouldn't care about that.
We can always read too much and throw the extra away :)

Jonathan

> +
> +Also see :doc:`iio_devbuf` for more general information.
>