Re: [PATCH] tpm.h: increase poll timings to fix tpm_tis regression

James Bottomley
2018-07-11T21:01:01Z

On Wed, 2018-07-11 at 22:51 +0200, Peter Huewe wrote:
>
> Am 11. Juli 2018 22:39:05 MESZ schrieb James Bottomley <James.Bottoml
> ey@HansenPartnership.com>:
> > On Wed, 2018-07-11 at 14:01 -0600, Jason Gunthorpe wrote:
> > > On Wed, Jul 11, 2018 at 12:08:53PM -0700, James Bottomley wrote:
> > > > On Wed, 2018-07-11 at 12:21 -0600, Jason Gunthorpe wrote:
[...]
> > > > > I wonder if something about triggering ETIME even once breaks
> > > > > the driver so it can't talk to the chip at all thereafter..
> > > > >
> > > > > Ie it doesn't abort the command properly and becomes desynced
> > > > > with the TIS execution protocol.
> > > >
> > > > Yes, I wondered about this, but I don't understand the bus
> > > > protocol well enough. The tpm-interface:tpm_try_transmit()
> > > > which throws the first ETIME says after we get that we send
> > > > chip->ops->cancel() which tpm_tis simply translates to
> > > > tpm_tis_ready() which also times out. Is there a bigger hammer
> > > > I can hit it with?
> > >
> > > I don't remember off hand.. But this is, IMHO, a better guess
> > > than the firmware crashes from reading the status register..
> >
> > Oh, actually, I think the bus crashes or wedges, not the TPM. I
> > just don't have any tools to probe the LPC.
> >
>
> I doubt that your fTPM is actually attached to LPC.
> And usually if lpc wedges it takes down your pc with it (from my
> experience)

How do I tell what it is attached to? Sysfs doesn't seem to know but I
assume the ACPI information should contain something relevant.

> I wonder what the contents of the acc and sts registers actually are.
>
>
> If you want i can send you a small tis 'debug' tool tomorrow.

Sure, that would help ... I'm just leafing through the TIS manual now
to see if there's anything I can build into the driver.

James