Re: [PATCH v5 16/17] tpm: take TPM chip power gating out of tpm_transmit()
From: Jarkko Sakkinen
Date: Thu Nov 08 2018 - 18:07:13 EST
On Thu, Nov 08, 2018 at 06:38:59PM +0000, Winkler, Tomas wrote:
> > Call tpm_chip_start() and tpm_chip_stop() in
> >
> > * tpm_try_get_ops() and tpm_put_ops()
> > * tpm_chip_register()
> > * tpm2_del_space()
> >
> > And remove these calls from tpm_transmit(). The core reason for this change
> > is that in tpm_vtpm_proxy a locality change requires a virtual TPM command
> > (a command made up just for that driver).
> >
> I don't think you can do that, locality has to be request for each
> command, as for example tboot can request higher locality any time.
That could be a potential problem. How tboot intervention gets prevented
without this patch?
> Same for cmd_ready()/go_idle() powergatin, you will prevent the whole
> platform entering power save state.
Why would you want that in a middle of using the TPM anyway?
> Thanks
> Tomas
/Jarkko