linux-kernel - Re: [PATCH v3] tpm: do not suspend/resume if power stays on

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Message-ID: <20170307185220.ag3hkthzeskg7le6@intel.com>
Date:   Tue, 7 Mar 2017 20:52:20 +0200
From:   Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:     Enric Balletbo i Serra <enric.balletbo@...labora.com>
Cc:     Rob Herring <robh+dt@...nel.org>, Peter Huewe <peterhuewe@....de>,
        Mark Rutland <mark.rutland@....com>,
        Jason Gunthorpe <jgunthorpe@...idianresearch.com>,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        tpmdd-devel@...ts.sourceforge.net,
        Sonny Rao <sonnyrao@...omium.org>
Subject: Re: [PATCH v3] tpm: do not suspend/resume if power stays on

On Tue, Mar 07, 2017 at 09:44:55AM +0100, Enric Balletbo i Serra wrote:
> Hi Jarkko,
> 
> On 06/03/17 21:59, Jarkko Sakkinen wrote:
> > On Fri, Mar 03, 2017 at 05:09:59PM +0100, Enric Balletbo i Serra wrote:
> >> From: Sonny Rao <sonnyrao@...omium.org>
> >>
> >> The suspend/resume behavior of the TPM can be controlled by setting
> >> "powered-while-suspended" in the DTS. This is useful for the cases
> >> when hardware does not power-off the TPM.
> >>
> >> Signed-off-by: Sonny Rao <sonnyrao@...omium.org>
> >> Signed-off-by: Enric Balletbo i Serra <enric.balletbo@...labora.com>
> >> ---
> >> Changes since v2:
> >>  Jarkko Sakkinen
> >>   - Add a new TPM_CHIP_FLAG_ALWAYS_POWERED flag instead of using a boolean variable.
> >>   - Remove a trailing newline.
> >> Changes since v1:
> >>  Jason Gunthorpe :
> >>   - Move the code to handle suspend/resume in the common chip code.
> >>
> >>  Documentation/devicetree/bindings/security/tpm/tpm-i2c.txt | 6 ++++++
> >>  drivers/char/tpm/tpm-interface.c                           | 3 +++
> >>  drivers/char/tpm/tpm.h                                     | 1 +
> >>  drivers/char/tpm/tpm_of.c                                  | 3 +++
> >>  4 files changed, 13 insertions(+)
> >>
> >> diff --git a/Documentation/devicetree/bindings/security/tpm/tpm-i2c.txt b/Documentation/devicetree/bindings/security/tpm/tpm-i2c.txt
> >> index 8cb638b..85c8216 100644
> >> --- a/Documentation/devicetree/bindings/security/tpm/tpm-i2c.txt
> >> +++ b/Documentation/devicetree/bindings/security/tpm/tpm-i2c.txt
> >> @@ -8,6 +8,12 @@ Required properties:
> >>                     the firmware event log
> >>  - linux,sml-size : size of the memory allocated for the firmware event log
> >>  
> >> +Optional properties:
> >> +
> >> +- powered-while-suspended: present when the TPM is left powered on between
> >> +                           suspend and resume (makes the suspend/resume
> >> +                           callbacks do nothing).
> >> +
> >>  Example (for OpenPower Systems with Nuvoton TPM 2.0 on I2C)
> >>  ----------------------------------------------------------
> > 
> > Hey, just noticed something. Shouldn't this be a separate commit?
> 
> During my life submitting patches I saw the both options, sometimes
> the maintainer asked me to join the DT patch and the driver and
> sometimes he asked me to do in different patches, so I think this is
> more a maintainer option. Maybe Rob Herring or Mark Rutland can share
> their preferences?
> 
> I'll do what you want I do, TBH I don't have a strong opinion about this.

I'll add this to my tree and put it to my next branch so that
it will flow to linux-next since it only touch TPM specific
file in bindings.

I do not have perfect answer for this so I'll use common sense
(or try to).

Rob, is this OK?

/Jarkko