On Thu, Apr 23, 2020 at 01:46:31PM +0800, peng.fan@nxp.com wrote:
> From: Peng Fan <peng.fan@nxp.com>
> 
> use clk_prepare at the very beginning will invoke pm runtime resume,
> if the clk is binded with a power domain. This will cause runtime
> power high. Let's use clk_prepare_enable and clk_disable_unprepare
> when read/write to avoid the runtime power issue.

This will mean that we're doing clk_prepare() during I/O which isn't
good since for MMIO regmaps we support I/O operations in atomic
contexts.