linux-kernel - Re: [PATCH v3 0/4] tpm/tpm_crb: implement power management.

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Message-ID: <20160914182540.GA5347@intel.com>
Date:   Wed, 14 Sep 2016 21:25:40 +0300
From:   Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:     "Winkler, Tomas" <tomas.winkler@...el.com>
Cc:     "jgunthorpe@...idianresearch.com" <jgunthorpe@...idianresearch.com>,
        "tpmdd-devel@...ts.sourceforge.net" 
        <tpmdd-devel@...ts.sourceforge.net>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 0/4] tpm/tpm_crb: implement power management.

On Wed, Sep 14, 2016 at 07:06:52PM +0300, Jarkko Sakkinen wrote:
> On Wed, Sep 14, 2016 at 07:06:02PM +0300, Jarkko Sakkinen wrote:
> > On Wed, Sep 14, 2016 at 06:28:03AM +0000, Winkler, Tomas wrote:
> > > On Mon, 2016-09-12 at 16:04 +0300, Tomas Winkler wrote:
> > > > Te overall platform ability to enter a low power state is also
> > > > conditioned on the ability of a tpm device to go to idle state.
> > > > This series should provide this feature.
> > > > 
> > > > Unfortunately, there is a HW bug on Intel PTT devices on Skylake,
> > > > Kabylake, and Broxton devices, where certain registers lost retention
> > > > during TPM idle state. Hence this implementation takes this into
> > > > consideration and implement the feature based only on access to
> > > > registers that retain their state. This still conforms to the spec
> > > > and should be correct also on non Intle devices.
> > > > 
> > > > V2: Utilize runtime_pm for driving tpm crb idle states.
> > > > V3. fix lower case corruption in the first patch
> > > > 
> > > Jarkko, had you chance to test v3 series one on your side, is this okay
> > > to go?
> > 
> > Opens for me are:
> > 
> > - pm_runtime_put_sync() is still used 
> > - callback names
> > - wait_for_tpm_stat

I think I got you wit with_for_tpm_stat. It's CRB specific internal
thing and thus using wait_for_tpm_stat would be abusing that function
and making it dependent on CRB driver internals.

Could you add a note on this to the commit message and I would be
find with your implementation.

I started to think about this after I wrote about callback names.

/Jarkko