Re: TPM selftest failure in 4.15

[Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>]

On Thu, Feb 08, 2018 at 09:02:00AM -0800, James Bottomley wrote:
> There is an identified regression: the TPM driver will now periodically
> fail to attach.  However, there's no point reviewing until we agree
> what the fix is.  I was just waiting to verify this fixed my problem
> (which means seeing the messages it spits out proving the TPM has
> remained in self test).  I have now seen this and the driver still
> works, so I can submit a formal patch.

For the self-test the duration falls down to 2 seconds as the specs do
not contain any well-defined duration for it, or at least I haven't
found it.

I see three alternative ways the fix the self-test:

1. Execute self-test with fullTest = YES.
2. Have a flag TPM_CHIP_TESTING that is set when the self-test is
   started. Issue a warning on time-out. Check for this flag in
   tpm_transmit_cmd() and tpm_write() and resend self-test command
   if the flag is stil test before the actual command. Return -EBUSY
   and print a warning if self-test is still active.
3. Increase the duration to the "correct" value if we have one.

/Jarkko