From: Ulf Hansson <ulf.hansson@linaro.org>
To: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Stephen Boyd <sboyd@kernel.org>,
Geert Uytterhoeven <geert+renesas@glider.be>,
Michael Turquette <mturquette@baylibre.com>,
"Rafael J . Wysocki" <rjw@rjwysocki.net>,
Kevin Hilman <khilman@kernel.org>,
Linux-Renesas <linux-renesas-soc@vger.kernel.org>,
linux-clk <linux-clk@vger.kernel.org>,
Linux PM list <linux-pm@vger.kernel.org>
Subject: Re: [PATCH 1/3] clk: renesas: mstp: Set GENPD_FLAG_ALWAYS_ON for clock domain
Date: Thu, 22 Aug 2019 16:06:10 +0200 [thread overview]
Message-ID: <CAPDyKFpr7fw_rCciXzZNk2is8KFkd7Tvdx-fzyka_vobCK0U=g@mail.gmail.com> (raw)
In-Reply-To: <CAMuHMdWpUEt-wxEdAK7NsAOadS5TtHYdO=JTGT=CtSROHuR+Pw@mail.gmail.com>
[...]
> >
> > Well is it actually a problem to not specify the flag? I guess it's just
> > a potential problem if the genpd is ever powered off, but given that the
> > governor decides to leave it always enabled it doesn't actually matter?
> > So it's not really fixing anything besides silencing a harmless warning?
>
> The warning is indeed harmless.
>
> The "interesting" case is the case where no warning is printed, as no
> IRQ-safe device is present. In that case, the absence of the
> GENPD_FLAG_ALWAYS_ON flag means that the core PM Domain code will
> consider the domain for power-off, and will loop over all devices part
> of it, which is suboptimal. Setting the flag avoids that.
>
> Thanks for your continued questions, it made me realize I need to add more
> meat to the description to these "simple" patches!
>
> For the PM people: would it make sense to add a
> WARN(!genpd->power_off && !genpd_is_always_on(genpd), "...") check to
> pm_genpd_init()?
> Or set GENPD_FLAG_ALWAYS_ON automatically if !genpd->power_off?
Well, wouldn't it be possible that the power is provided through a
master domain, thus not having the ->power_off() callback assigned for
the subdomain is perfectly fine, even without having
GENPD_FLAG_ALWAYS_ON not set.
Kind regards
Uffe
next prev parent reply other threads:[~2019-08-22 14:06 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-16 12:52 [PATCH 0/3] clk: renesas: Set GENPD_FLAG_ALWAYS_ON for clock domain Geert Uytterhoeven
2019-08-16 12:52 ` [PATCH 1/3] clk: renesas: mstp: " Geert Uytterhoeven
2019-08-16 15:38 ` Simon Horman
2019-08-16 18:01 ` Stephen Boyd
2019-08-16 19:59 ` Geert Uytterhoeven
2019-08-17 3:48 ` Stephen Boyd
2019-08-18 8:27 ` Geert Uytterhoeven
2019-08-22 14:06 ` Ulf Hansson [this message]
2019-08-23 8:59 ` Geert Uytterhoeven
2019-08-16 12:52 ` [PATCH 2/3] clk: renesas: r9a06g032: " Geert Uytterhoeven
2019-08-16 15:39 ` Simon Horman
2019-08-16 12:52 ` [PATCH 3/3] clk: renesas: cpg-mssr: " Geert Uytterhoeven
2019-08-16 15:39 ` Simon Horman
2019-08-22 14:08 ` [PATCH 0/3] clk: renesas: " Ulf Hansson
2019-08-23 9:08 ` Geert Uytterhoeven
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