Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
MIME-Version: 1.0
References: <20220131113743.52265-1-ulf.hansson@linaro.org>
 <b33ceac4-506a-65c8-7c80-b1b0a67ce65e@gmail.com> <CAPDyKFqsvF=Pm-vMXSUwPMPnjCr7nSYuy5AH+8rwLYm_NUPKww@mail.gmail.com>
 <400e45da-837a-c8ad-84b3-285e35f8462c@gmail.com> <CAPDyKFpLX0Jpz-tzYx3-g0YBZZNh6Bw731gQEFQub1SviLGoYg@mail.gmail.com>
 <2656099c-76bc-33a5-3b98-c46858025955@gmail.com>
In-Reply-To: <2656099c-76bc-33a5-3b98-c46858025955@gmail.com>
From:   Ulf Hansson <ulf.hansson@linaro.org>
Date:   Mon, 14 Feb 2022 10:22:32 +0100
Message-ID: <CAPDyKFokevJSYoH009t3PA4h48tx-LK+DaWVpC_14L6xZF3iZA@mail.gmail.com>
Subject: Re: [PATCH] PM: domains: Prevent power off for parent unless child is
 in deepest state
To:     Dmitry Osipenko <digetx@gmail.com>
Cc:     "Rafael J . Wysocki" <rafael@kernel.org>, linux-pm@vger.kernel.org,
        Kevin Hilman <khilman@kernel.org>,
        Alexandre Torgue <alexandre.torgue@foss.st.com>,
        Geert Uytterhoeven <geert+renesas@glider.be>,
        Rajendra Nayak <rnayak@codeaurora.org>,
        Dong Aisheng <aisheng.dong@nxp.com>,
        linux-kernel@vger.kernel.org
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
Precedence: bulk

On Sun, 13 Feb 2022 at 13:14, Dmitry Osipenko <digetx@gmail.com> wrote:
>
> 07.02.2022 11:43, Ulf Hansson =D0=BF=D0=B8=D1=88=D0=B5=D1=82:
> >> In general, such changes usually are deferred from being upstreamed
> >> until there is a real user, otherwise there is a risk of cluttering th=
e
> >> code with unused features. Do you have a time estimation in regards to
> >> when STMicro may start to benefit from this change?
> > The STMicro folkz are working on it right now, but I can't give you
> > any estimates for their work.
> >
> > Moreover, I think the important point in this regard, is that the
> > $subject patch doesn't really hurt anything else, so then what's the
> > point of holding this back?
>
> If that work will never pan out, will you remove the unused code?

Sure, I will continue to monitor the situation, which is what I have
been doing for many years by now.

In the past we have agreed to add new things to genpd, even if those
didn't have in-tree users when the changes went in. The current
dev_pm_genpd_set_next_wakeup() inteface, for example, is still lacking
a user upstream. It's a balance, because I certainly agree with you,
that we don't want to carry around dead code in the kernel - unless we
have reasons to believe it's an intermediate step before there a user
turning up.

Kind regards
Uffe