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

[Winkler, Tomas]

> 
> 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?
As it was said, need to request locality and relinquish it for each command, I believe thought this is not required for client platforms only for servers. 
> 
> > 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?
If I'm reading this patch correctly you do cmd_ready when tpm is opened, it doesn't mean there is a real traffic, so why to keep it awake. 
Thanks
Tomas