Re: [PATCH] I2C: Fix for suspend/resume issue in i2c-core

[Mark Brown <broonie@opensource.wolfsonmicro.com>]

On Mon, Aug 30, 2010 at 11:43:23AM -0700, Kevin Hilman wrote:
> Vishwanath BS <vishwanath.bs@ti.com> writes:
> 
> > In current i2c core driver, pm_runtime_set_active call from i2c_device_pm_resume
> > is not balanced by pm_runtime_set_suspended call from i2c_device_pm_suspend.
> > pm_runtime_set_active called from resume path will increase the child_count of
> > the device's parent. However, matching pm_runtime_set_suspended is not called
> > in suspend routine because of which child_count of the device's parent
> > is not balanced, preventing the parent device to idle.
> > Issue has been fixed by adding pm_runtime_set_suspended call inside suspend
> > reoutine which will make sure that child_counts are balanced.
> > This fix has been tested on OMAP4430.
> >
> > Signed-off-by: Partha Basak <p-basak2@ti.com>
> > Signed-off-by: Vishwanath BS <vishwanath.bs@ti.com>
> >
> > Cc: Rafael J. Wysocki <rjw@sisk.pl>
> > Cc: Kevin Hilman <khilman@deeprootsystems.com>
> > Cc: Ben Dooks <ben-linux@fluff.org>
> 
> Also Cc'ing Mark Brown as original author of runtime PM for i2-core.

Also Jean Delvare who maintains the I2C core.  To be honest Rafael did
all the actual work here (and has since rewritten the code anyway).

> > ---
> >  drivers/i2c/i2c-core.c |   12 ++++++++++--
> >  1 files changed, 10 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
> > index 6649176..3146bff
> > --- a/drivers/i2c/i2c-core.c
> > +++ b/drivers/i2c/i2c-core.c
> > @@ -196,14 +196,22 @@ static int i2c_legacy_resume(struct device *dev)
> >  static int i2c_device_pm_suspend(struct device *dev)
> >  {
> >  	const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
> > +	int ret;
> >  
> >  	if (pm_runtime_suspended(dev))
> >  		return 0;
> >  
> >  	if (pm)
> > -		return pm->suspend ? pm->suspend(dev) : 0;
> > +		ret = pm->suspend ? pm->suspend(dev) : 0;
> > +	else
> > +		ret = i2c_legacy_suspend(dev, PMSG_SUSPEND);
> >  
> > -	return i2c_legacy_suspend(dev, PMSG_SUSPEND);
> > +	if (!ret) {
> > +		pm_runtime_disable(dev);
> > +		pm_runtime_set_suspended(dev);
> > +		pm_runtime_enable(dev);
> > +	}
> > +	return ret;
> >  }
> >  
> >  static int i2c_device_pm_resume(struct device *dev)