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

On Sun, Dec 14, 2014 at 09:48:26AM -0500, Stefan Berger wrote:

On 12/12/2014 02:46 PM, Jarkko Sakkinen wrote:

quoted

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