On Thu, Sep 21, 2023 at 5:45 PM Rob Herring <robh@xxxxxxxxxx> wrote: > > 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: > > ... > > - 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. > This one is a bit of a gray area since it could be either way. The chip has two input pins for selecting the resolution. If the hardware designer decides to connect these to gpios, then they could be changed at runtime. But if the hardware designer decides to hard-wire these pins then we need to supply this information via the devicetree. The choice of the resolution is determined by the physical requirements of the full system. This device measures rotational position and velocity. So the main reason to pick something less than the full 16-bit resolution is if the max rotational speed of whatever is connected is going to be greater than 125 revolutions per second (assuming 8.192 MHz clock).
