From: Stephen Boyd <sboyd@kernel.org>
To: Miquel Raynal <miquel.raynal@bootlin.com>
Cc: Gregory Clement <gregory.clement@bootlin.com>,
Antoine Tenart <antoine.tenart@bootlin.com>,
Michael Turquette <mturquette@baylibre.com>,
linux-kernel@vger.kernel.org,
Russell King <linux@armlinux.org.uk>,
Nadav Haklai <nadavh@marvell.com>,
Thomas Petazzoni <thomas.petazzoni@bootlin.com>,
Maxime Chevallier <maxime.chevallier@bootlin.com>,
linux-clk@vger.kernel.org, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v3 1/4] clk: core: clarify the check for runtime PM
Date: Thu, 20 Dec 2018 13:09:19 -0800 [thread overview]
Message-ID: <154534015908.79149.14109221006631310404@swboyd.mtv.corp.google.com> (raw)
In-Reply-To: <20181219090331.4c8c4852@xps13>
Quoting Miquel Raynal (2018-12-19 00:03:31)
> Hi Stephen,
>
> Stephen Boyd <sboyd@kernel.org> wrote on Tue, 18 Dec 2018 16:03:29
> -0800:
>
> > Quoting Miquel Raynal (2018-12-04 11:24:37)
> > > Currently, the core->dev entry is populated only if runtime PM is
> > > enabled. Doing so prevents accessing the device structure in any
> > > case.
> > >
> > > Keep the same logic but instead of using the presence of core->dev as
> > > the only condition, also check the status of
> > > pm_runtime_enabled(). Then, we can set the core->dev pointer at any
> > > time as long as a device structure is available.
> > >
> > > This change will help supporting device links in the clock subsystem.
> > >
> > > Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
> > > ---
> > > drivers/clk/clk.c | 11 +++++------
> > > 1 file changed, 5 insertions(+), 6 deletions(-)
> > >
> > > diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
> > > index af011974d4ec..b799347c5fd6 100644
> > > --- a/drivers/clk/clk.c
> > > +++ b/drivers/clk/clk.c
> > > @@ -97,7 +97,7 @@ static int clk_pm_runtime_get(struct clk_core *core)
> > > {
> > > int ret = 0;
> > >
> > > - if (!core->dev)
> > > + if (!core->dev || !pm_runtime_enabled(core->dev))
> >
> > This looks potentially dangerous. What if runtime PM is disabled for the
> > clk when this function is called? Shouldn't we just stash a bool away in
> > the clk_core structure when it's registered? And then we can replace the
> > check for !core->dev with a check for 'core->rpm_enabled' instead. That
> > would be a more exact transformation.
>
> Sure, I'll do that if you think there is a danger.
I've made the change and pushed it out to the clk tree. I'm working on
some patches to change how we do parent lookups and reworking clk_get()
in the process. Take a look so we don't duplicate efforts. The code
isn't complete, but I hope to finish soon. Your device links patches can
build upon this.
git://git.kernel.org/pub/scm/linux/kernel/git/clk/linux.git clk-parent-rewrite
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next prev parent reply other threads:[~2018-12-20 21:09 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-04 19:24 [PATCH v3 0/4] Add device links to clocks Miquel Raynal
2018-12-04 19:24 ` [PATCH v3 1/4] clk: core: clarify the check for runtime PM Miquel Raynal
2018-12-19 0:03 ` Stephen Boyd
2018-12-19 8:03 ` Miquel Raynal
2018-12-20 21:09 ` Stephen Boyd [this message]
2019-01-02 10:55 ` Miquel Raynal
2018-12-04 19:24 ` [PATCH v3 2/4] clk: core: link consumer with clock driver Miquel Raynal
2018-12-11 17:12 ` Stephen Boyd
2018-12-17 14:24 ` Miquel Raynal
2019-01-04 15:54 ` Miquel Raynal
2019-01-25 21:28 ` Stephen Boyd
2019-01-28 10:06 ` Miquel Raynal
2018-12-04 19:24 ` [PATCH v3 3/4] clk: mvebu: armada-37xx-tbg: fill the device entry when registering the clocks Miquel Raynal
2018-12-04 19:24 ` [PATCH v3 4/4] clk: mvebu: armada-37xx-xtal: fill the device entry when registering the clock Miquel Raynal
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