tree deacbb011383a6a95922b8c49cd3c8e77c34afd2
parent 45baa1d1fa3926510ead93c96e6b0baa5ad79bd3
author Stefan Berger <stefanb@linux.vnet.ibm.com> 1301501611 -0400
committer Rajiv Andrade <srajiv@linux.vnet.ibm.com> 1310507588 -0300

tpm_tis: Delay ACPI S3 suspend while the TPM is busy

This patch delays the (ACPI S3) suspend while the TPM is busy processing a
command and the TPM TIS driver is run in interrupt mode. This is the same
behavior as we already have it for the TPM TIS driver in polling mode.

Reasoning: Some of the TPM's commands advance the internal state of the TPM.
An example would be the extending of one of its PCR registers. Upper layers,
such as IMA or TSS (TrouSerS), would certainly want to be sure that the
command succeeded rather than getting an error code (-62 = -ETIME) that may
not give a conclusive answer as for what reason the command failed. Reissuing
such a command would put the TPM into the wrong state, so waiting for it to
finish is really the only option.

The downside is that some commands (key creation) can take a long time and
actually prevent the machine from entering S3 at all before the 20 second
timeout of the power management subsystem arrives.

Signed-off-by: Stefan Berger <stefanb@linux.vnet.ibm.com>
Signed-off-by: Rajiv Andrade <srajiv@linux.vnet.ibm.com>