linux-kernel - RE: [PATCH] tpm/tpm_crb: enter the low power state upon device suspend

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Date:   Mon, 6 Mar 2017 18:19:59 +0000
From:   "Winkler, Tomas" <tomas.winkler@...el.com>
To:     Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
CC:     "tpmdd-devel@...ts.sourceforge.net" 
        <tpmdd-devel@...ts.sourceforge.net>,
        Jason Gunthorpe <jgunthorpe@...idianresearch.com>,
        "linux-security-module@...r.kernel.org" 
        <linux-security-module@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH] tpm/tpm_crb: enter the low power state upon device
 suspend


> 
> On Mon, Mar 06, 2017 at 01:53:35AM +0200, Tomas Winkler wrote:
> > This fix enables a platform to enter the idle state (suspend-to-idle)
> >
> > The driver needs to request explicitly go_idle upon completion from
> > the pm suspend handler.
> > The runtime pm is disabled on suspend during prepare state by calling
> > pm_runtime_get_noresume, hence we cannot relay on runtime pm to leave
> > the device in low power state. Symmetrically cmdReady is called upon
> > resume.
> >
> > Signed-off-by: Tomas Winkler <tomas.winkler@...el.com>
> 
> LGTM
> 
> Tested-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
> Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
> 
> PS. What about Fixes? Does this need it?

No, I don't think this is a regression caused by any patch, rather the pm solution was not complete.
Thanks  
Tomas

 
> /Jarkko
> 
> > ---
> >  drivers/char/tpm/tpm_crb.c | 25 ++++++++++++++++++++++++-
> >  1 file changed, 24 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/char/tpm/tpm_crb.c b/drivers/char/tpm/tpm_crb.c
> > index 86f355b6df1d..d8dfff0fdfce 100644
> > --- a/drivers/char/tpm/tpm_crb.c
> > +++ b/drivers/char/tpm/tpm_crb.c
> > @@ -479,10 +479,33 @@ static int crb_pm_runtime_resume(struct device
> > *dev)
> >
> >  	return crb_cmd_ready(dev, priv);
> >  }
> > +
> > +static int crb_pm_suspend(struct device *dev) {
> > +	int ret;
> > +
> > +	ret = tpm_pm_suspend(dev);
> > +	if (ret)
> > +		return ret;
> > +
> > +	return crb_pm_runtime_suspend(dev);
> > +}
> > +
> > +static int crb_pm_resume(struct device *dev) {
> > +	int ret;
> > +
> > +	ret = crb_pm_runtime_resume(dev);
> > +	if (ret)
> > +		return ret;
> > +
> > +	return tpm_pm_resume(dev);
> > +}
> > +
> >  #endif /* CONFIG_PM */
> >
> >  static const struct dev_pm_ops crb_pm = {
> > -	SET_SYSTEM_SLEEP_PM_OPS(tpm_pm_suspend, tpm_pm_resume)
> > +	SET_SYSTEM_SLEEP_PM_OPS(crb_pm_suspend, crb_pm_resume)
> >  	SET_RUNTIME_PM_OPS(crb_pm_runtime_suspend,
> crb_pm_runtime_resume,
> > NULL)  };
> >
> > --
> > 2.7.4
> >