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

[Jason Gunthorpe]

On Tue, Apr 04, 2017 at 06:29:06PM +0200, Paul Menzel wrote:

> Unfortunately, there seems to have been a regression between Linux 3.16 
> and 4.8 and 4.9, so that the Linux kernel doesnât create the TPM
> device.

That old kernel did not check error codes when reading burst count,
the new one does. It is quite possible the older kernel is failing to
read burst count and subtly malfunctioning.

It would be helpful if you could prove/disprove this statement by
adding some debugging to 3.16.

As to why the burst count cannot be read.. I don't know, check if
increasing the retries helps, it could be this particular TPM is out
of spec for the cold startup process.

> Remove module and run `sudo modprobe tpm_tis itpm=1 force=1`.

Is this really an 'itpm'? It doesn't look like it..

Jason