Re: [tpmdd-devel] [PATCH] tpm: do not suspend/resume if power stays on

From	Sonny Rao <sonnyrao@chromium.org>
Newsgroups	linux.kernel
Subject	Re: [tpmdd-devel] [PATCH] tpm: do not suspend/resume if power stays on
Date	2017-03-01 23:40 +0100
Message-ID	<tgl4B-1eE-7@gated-at.bofh.it> (permalink)
References	<tgb5g-2A8-21@gated-at.bofh.it> <tgcXo-3Po-23@gated-at.bofh.it> <tgiq5-7Fz-17@gated-at.bofh.it>
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On Wed, Mar 1, 2017 at 10:43 AM, Jason Gunthorpe
<jgunthorpe@obsidianresearch.com> wrote:
>> > +Optional properties:
>> > +- powered-while-suspended: present when the TPM is left powered on between
>> > +  suspend and resume (makes the suspend/resume callbacks do nothing).
>>
>> This reads like configuration rather than a HW property.
>
> I read this to mean the HW does not cut power to the TPM when Linux
> does 'suspend'.

That's correct, it is a hardware property describing whether power is
removed during suspend.

>
> We recently added global suspend/resume callbacks to the TPM
> core. Those call backs do not power off the TPM, they just prepare its
> internal state to loose power to the chip. Skipping that process on
> hardware that does not power-off the TPM makes sense to me.
>
> But, Sonny, perhaps this should be a global flag in tpm_chip, not a
> per-interface-driver override?

It's a property of the board design not the chip -- maybe I'm misunderstanding?

>
> Jason

Thread

[PATCH] tpm: do not suspend/resume if power stays on Enric Balletbo i Serra <enric.balletbo@collabora.com> - 2017-03-01 13:00 +0100
  Re: [PATCH] tpm: do not suspend/resume if power stays on Peter Huewe <peterhuewe@gmx.de> - 2017-03-01 13:10 +0100
    Re: [PATCH] tpm: do not suspend/resume if power stays on Enric Balletbo i Serra <enric.balletbo@collabora.com> - 2017-03-01 13:20 +0100
  Re: [PATCH] tpm: do not suspend/resume if power stays on Mark Rutland <mark.rutland@arm.com> - 2017-03-01 15:00 +0100
    Re: [tpmdd-devel] [PATCH] tpm: do not suspend/resume if power stays  on Jason Gunthorpe <jgunthorpe@obsidianresearch.com> - 2017-03-01 20:50 +0100
      Re: [tpmdd-devel] [PATCH] tpm: do not suspend/resume if power stays on Sonny Rao <sonnyrao@chromium.org> - 2017-03-01 23:40 +0100
        Re: [tpmdd-devel] [PATCH] tpm: do not suspend/resume if power stays on Sonny Rao <sonnyrao@chromium.org> - 2017-03-02 01:10 +0100
        Re: [tpmdd-devel] [PATCH] tpm: do not suspend/resume if power stays  on Jason Gunthorpe <jgunthorpe@obsidianresearch.com> - 2017-03-02 01:50 +0100

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