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Date: Thu, 21 Sep 2023 10:45:14 -0500
From: Rob Herring <robh@kernel.org>
To: David Lechner <dlechner@baylibre.com>
Cc: linux-iio@vger.kernel.org, devicetree@vger.kernel.org, linux-staging@lists.linux.dev, linux-kernel@vger.kernel.org, Jonathan Cameron <jic23@kernel.org>, Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>, Conor Dooley <conor+dt@kernel.org>, Michael Hennerich <Michael.Hennerich@analog.com>, Nuno =?iso-8859-1?Q?S=E1?= <nuno.sa@analog.com>, Axel Haslam <ahaslam@baylibre.com>, Philip Molloy <pmolloy@baylibre.com>
Subject: Re: [PATCH 4/4] iio: resolver: add new driver for AD2S1210
Message-ID: <20230921154514.GA383967-robh@kernel.org>
References: <20230920170253.203395-1-dlechner@baylibre.com>
 <20230920170253.203395-5-dlechner@baylibre.com>
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In-Reply-To: <20230920170253.203395-5-dlechner@baylibre.com>

On Wed, Sep 20, 2023 at 12:02:53PM -0500, David Lechner wrote:
> This adds a new driver for Analog Devices, Inc. AD2S1210 resolver to
> digital converter. The driver is based on the staging driver with the
> following improvements:
> 
> Fixes:
> - Fix use before initialization bug in probe.
> - Fix not checking error returns in probe.
> - Remove spi_setup() and spi_set_drvdata() from probe.
> - Fix ordering of devm_iio_device_register()
> - Remove incorrect hysteresis logic
> 
> Changes:
> - Use BIT/GENMASK macros.
> - Use devicetree to get CLKIN frequency (was sysfs attribute).
> - No longer bit-shift the raw value for IIO_CHAN_INFO_RAW.
> - Use regmap for register access.
> - Remove config sysfs attribute.
> - Use gpio array for mode and resolution gpios.
> - Invert sample gpio logic and use GPIO_ACTIVE_LOW in devicetree.
> - Change hysteresis to use IIO_CHAN_INFO_HYSTERESIS instead of custom
>   device attribute.
> - Rename fexcit attribute to excitation_frequency.
> - Use devicetree to specify resolution instead of sysfs attribute.

Why? sysfs allows a user to change at run-time. DT is a firmware 
change. What/who determines the resolution? Unless it's the hardware 
design/designer, it probably doesn't belong in DT.

Rob