From mboxrd@z Thu Jan  1 00:00:00 1970
From: Mika Westerberg <mika.westerberg@linux.intel.com>
Subject: Re: [PATCH v2 1/9] i2c: prepare runtime PM support for I2C client
 devices
Date: Fri, 13 Sep 2013 09:54:34 +0300
Message-ID: <20130913065434.GZ7393@intel.com>
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 <87vc25pvvm.fsf@linaro.org>
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To: Kevin Hilman <khilman@linaro.org>
Cc: linux-i2c@vger.kernel.org, Wolfram Sang <wsa@the-dreams.de>, "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>, linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org, Lv Zheng <lv.zheng@intel.com>, Aaron Lu <aaron.lu@intel.com>, linux-arm-kernel@lists.infradead.org, Mark Brown <broonie@kernel.org>, Dmitry Torokhov <dmitry.torokhov@gmail.com>, Mauro Carvalho Chehab <m.chehab@samsung.com>, Samuel Ortiz <sameo@linux.intel.com>, Lee Jones <lee.jones@linaro.org>, Arnd Bergmann <arnd@arndb.de>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Liam Girdwood <lgirdwood@gmail.com>, Kyungmin Park <kyungmin.park@samsung.com>
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On Thu, Sep 12, 2013 at 02:34:21PM -0700, Kevin Hilman wrote:
> > diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
> > index f32ca29..44374b4 100644
> > --- a/drivers/i2c/i2c-core.c
> > +++ b/drivers/i2c/i2c-core.c
> > @@ -248,11 +248,30 @@ static int i2c_device_probe(struct device *dev)
> >  					client->flags & I2C_CLIENT_WAKE);
> >  	dev_dbg(dev, "probe\n");
> >  
> > +	/* Make sure the adapter is active */
> > +	pm_runtime_get_sync(&client->adapter->dev);
> > +
> > +	/*
> > +	 * Enable runtime PM for the client device. If the client wants to
> > +	 * participate on runtime PM it should call pm_runtime_put() in its
> > +	 * probe() callback.
> > +	 */
> > +	pm_runtime_get_noresume(&client->dev);
> > +	pm_runtime_set_active(&client->dev);
> 
> Why the set_active here?
> 
> For hardware that is disabled/powered-off on startup, there will now be
> a mismatch between the hardware state an the RPM core state.

The call to pm_runtime_get_noresume() should make sure that the device is
in active state (at least in state where it can access the bus) if I'm
understanding this right.