Re: [PATCH v5 16/17] tpm: take TPM chip power gating out of tpm_transmit()

[Jarkko Sakkinen]

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