Re: [PATCH] tpm, tpm_tis: fix TPM 2.0 probing

[Stefan Berger <stefanb-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>]

On 02/09/2015 03:39 AM, Jarkko Sakkinen wrote:
> On Mon, Feb 09, 2015 at 12:08:46AM +0100, Peter Hüwe wrote:
>> Am Mittwoch, 4. Februar 2015, 15:21:09 schrieb Jarkko Sakkinen:
>>> If during transmission system error was returned, the logic was to
>>> incorrectly deduce that chip is a TPM 1.x chip. This patch fixes this
>>> issue. Also, this patch changes probing so that message tag is used as the
>>> measure for TPM 2.x, which should be much more stable.
>> Is it aware that some TPMs may respond with 0x00C1 as TAG for TPM1.2 commands?
> I guess none of the TPM 1.2 command answer with the tag 0x8002?


FYI: pdf page 26 , section 6.1 explains the predictable return value for 
a TPM1.2 command seen by a TPM2

http://www.trustedcomputinggroup.org/files/static_page_files/8C68ADA8-1A4B-B294-D0FC06D3773F7DAA/TPM%20Rev%202.0%20Part%203%20-%20Commands%2001.16-code.pdf

Following this:

Sending a TPM1.2 command to a TPM2 should return a TPM1.2 header (tag = 
0xc4) and error code (TPM_BADTAG = 0x1e)

Sending a TPM 2 command to a TPM 2 will give a TPM 2 tag in the header.
Sending a TPM 2 command to a TPM 1.2 will give a TPM 1.2 tag in the 
header and an error code.


    Stefan