Re: [PATCH v10 8/8] tpm: TPM 2.0 FIFO Interface

[Jarkko Sakkinen <jarkko.sakkinen-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>]

On Sun, Dec 14, 2014 at 09:48:26AM -0500, Stefan Berger wrote:
> On 12/12/2014 02:46 PM, Jarkko Sakkinen wrote:
> >Detect TPM 2.0 by sending idempotent TPM 2.x command. Ordinals for
> >TPM 2.0 are higher than TPM 1.x commands so this should be fail-safe.
> >Using STS3 is unreliable because some chips just report 0xff and not
> >what the spec says.
> 
> TPM TIS 1.2 can report either 0xff or 0x00 for sts3 since that part of
> register was not defined for this version but only for a later version. So,
> unless the TIS 1.3 for TPM 2.0 is broken, it should report a bit _pattern_
> (not plain 0x00 or 0xff) that you could apply the suggested mask to and
> check then.

I propose this: lets keep the bit ugly but approach for now and when 
there are TPM2 FIFOs available in the market move to your workaround. 
I think that would be the most reasonable middle road here.

>     Stefan

/Jarkko