Re: [RFC LINUX PATCH] dt: xilinx: xadc: provision to control clock frequency

From: SÃren Brinkmann
Date: Wed Dec 23 2015 - 06:48:14 EST


On Wed, 2015-12-23 at 03:58PM +0530, Ranjit Waghmode wrote:
> This patch adds parameter to the xilinx-xadc node for controlling
> clock frequency.
>
> Following are the possible options for user to control the frequency:
> * 00 : 1/2 of clock frequency
> * 01 : 1/4 of clock frequency
> * 10 : 1/8 of clock frequency
> * 11 : 1/16 of clock frequency

How is this chosen? Are these just arbitrary values that you need for
some use-case? Or are these the options HW allows?

>
> So this patch adds parameter tck-rate to set user defined values from
> above pool to control the clock frequency.

This is no longer describing HW, but configuring driver/HW. Why does
this have to be in DT? Why can't the driver request/set the frequency as
operation requires it?

Thanks,
SÃren
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