Re: [tpmdd-devel] Regression between Linux 3.16 and 4.8/4.9 on Lenovo X60 with coreboot

Denis 'GNUtoo' Carikli
2017-04-08T11:26:08Z

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Hi Paul,

On Thu, 6 Apr 2017 10:55:57 -0600
Jason Gunthorpe <jgunthorpe@obsidianresearch.com> wrote:

> We added direct ACPI binding to the driver in addition to PNP, so if
> you have an ACPI table it goes down that path and does some additional
> validation of what is in the TPM. The BIOS must provide a
> acpi_dev_resource_memory and a ACPI_SIG_TPM2 for the ACPI entry at a
> minimum.

I am working on it[1]. This commit has not been merged and is a work in
progress. It is however available in coreboot's gerrit.

So far with it and a recent kernel and the patch mentioned above:
- The linux driver finds the TPM automatically and doesn't require
force=1
- The driver however still require itpm=1 to fully work: without it the
tpm is found, but I wasn't able to read the PCRs.

Since I use a rolling release distribution, the kenrel version I use
tend to change quite fast, I can re-test if needed.

I need to improve the following in my patch:
- The IDs readings obviously need to be fixed.
- I want to make it work without itpm=1 if possible. I'll test with
INTC0102 as it is in the driver in the is_itpm function, and it was
also suggested to me by someone on IRC.

I also still need to investigate more why the itpm workaround is needed.
Does the TPM shipped in such laptops respect the specifications?
Is the wiring bad?

References:
-----------
[1]https://review.coreboot.org/cgit/coreboot.git/commit/?id=060cf4e0f50f765f85e3ecedd836eed85d1571fe

Denis.

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