linux-kernel - Re: [RFC 10/11] reset: imx: Add audiomix reset controller support

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Date:   Fri, 13 Mar 2020 16:55:47 +0100
From:   Philipp Zabel <p.zabel@...gutronix.de>
To:     Abel Vesa <abel.vesa@....com>
Cc:     Rob Herring <robh@...nel.org>, Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <kernel@...gutronix.de>,
        Fabio Estevam <fabio.estevam@....com>,
        Mike Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Lee Jones <lee.jones@...aro.org>,
        Anson Huang <anson.huang@....com>,
        Leonard Crestez <leonard.crestez@....com>,
        Peng Fan <peng.fan@....com>, Jacky Bai <ping.bai@....com>,
        devicetree@...r.kernel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        NXP Linux Team <linux-imx@....com>,
        linux-clk@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [RFC 10/11] reset: imx: Add audiomix reset controller support

On Fri, 2020-03-13 at 16:16 +0200, Abel Vesa wrote:
[...]
> > > +	if (assert) {
> > > +		pm_runtime_get_sync(rcdev->dev);
> > 
> > This seems wrong. Why is the runtime PM reference count incremented when
> > a reset is asserted ...
> 
> The audiomix IP has its own power domain. 

The reset controller does not control the power domain for its
consumers. The consumer of this reset should implement runtime PM.

> The way I see it, when the last deassert is done, there is no point
> in keeping the audiomix on. So, unless the clock controller part of it does it,
> the audiomix will be powered down.

You mean when the last assert is done? Presumably the driver wants to
use the hardware after deasserting the reset and asserts the reset when
it is done.

regards
Philipp