linux-kernel - Re: [RFC PATCH 1/2] PM: domains: Allow devices attached to genpd to be managed by HW

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Date:   Tue, 27 Jun 2023 13:54:06 +0300
From:   Abel Vesa <abel.vesa@...aro.org>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     "Rafael J . Wysocki" <rafael@...nel.org>,
        Kevin Hilman <khilman@...nel.org>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        avel Machek <pavel@....cz>, Len Brown <len.brown@...el.com>,
        Bjorn Andersson <andersson@...nel.org>,
        Andy Gross <agross@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        Mike Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Taniya Das <tdas@....qualcomm.com>, linux-pm@...r.kernel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-arm-msm@...r.kernel.org
Subject: Re: [RFC PATCH 1/2] PM: domains: Allow devices attached to genpd to
 be managed by HW

On 23-06-27 12:46:28, Greg Kroah-Hartman wrote:
> On Tue, Jun 27, 2023 at 01:40:32PM +0300, Abel Vesa wrote:
> > From: Ulf Hansson <ulf.hansson@...aro.org>
> > 
> > Some power-domains may be capable of relying on the HW to control the power
> > for a device that's hooked up to it. Typically, for these kinds of
> > configurations the device doesn't really need to be attached to a PM domain
> > (genpd), from Linux point of view. However, in some cases the behaviour of
> > the power-domain and its device can be changed in runtime.
> > 
> > To allow a consumer driver to change the behaviour of the PM domain for its
> > device, let's provide a new function, dev_pm_genpd_set_hwmode(). Moreover,
> > let's add a corresponding optional genpd callback, ->set_hwmode_dev(),
> > which the genpd provider should implement if it can support switching
> > between HW controlled mode and SW controlled mode.
> > 
> > Signed-off-by: Ulf Hansson <ulf.hansson@...aro.org>
> 
> You can't forward on a patch from someone else without also adding your
> signed-off-by on it, right?

Oups, forgot to add it. Will do in the next version.

> 
> Also, why is this a RFC series?  What is left to do with it to get it
> into a state which you feel comfortable having us review it "for real"?

There is a bit of back story here. This HW control support is something
that Qualcomm platforms support for some of the PDs. Sent this as RFC
as I thought it might open up a discussion of such a generic need at
first. But now that I think of it, it might've been a non-RFC patch as
well.

> 
> thanks,
> 
> greg k-h