Dear Linux folks,
Currently, TPM support is added to the coreboot project for the Lenovo
X60 [1].
Unfortunately, there seems to have been a regression between Linux 3.16
and 4.8 and 4.9, so that the Linux kernel doesn’t create the TPM device.
```
$ more /proc/version Linux version 3.16.0-4-686-pae
(debian-ker...@lists.debian.org) (gcc version 4.8.4 (Debian 4.8.4-1) )
#1 SMP Debian 3.16.39-1+deb8u2 (2017-03-07)
$ journalctl -k -o cat | grep -i tpm
tpm_tis 00:08: 1.2 TPM (device-id 0x3202, rev-id 5)
tpm_tis 00:08: Issuing TPM_STARTUP
```
The device `/dev/tpm0` is present.
Here are the results with Linux 4.8.15.
```
kernel: [ 0.000000] Linux version 4.8.0-0.bpo.2-686-pae
(debian-ker...@lists.debian.org) (gcc version 4.9.2 (Debian 4.9.2-10) )
#1 SMP Debian 4.8.15-2~bpo8+2 (2017-01-17)
[…]
kernel: [ 11.302522] tpm tpm0: tpm_transmit: tpm_send: error -5
kernel: [ 11.302598] tpm_tis 00:08: Could not get TPM timeouts and
durations
```
Remove module and run `sudo modprobe tpm_tis itpm=1 force=1`.
```
kernel: [ 35.024386] tpm_tis tpm_tis: 1.2 TPM (device-id 0x3202, rev-id 5)
kernel: [ 49.160752] tpm_tis 00:08: can't request region for resource
[mem 0xfed40000-0xfed44fff]
kernel: [ 49.160865] tpm_tis: probe of 00:08 failed with error -16
```
And here with Linux 4.9.13.
```
kernel: [ 7.813547] tpm_tis 00:08: 1.2 TPM (device-id 0x3202, rev-id 5)
kernel: [ 7.891026] tpm tpm0: Issuing TPM_STARTUP
kernel: [ 8.042783] tpm tpm0: Unable to read burstcount
kernel: [ 8.042893] tpm tpm0: tpm_transmit: tpm_send: error -16
kernel: [ 8.042900] tpm_tis 00:08: Could not get TPM timeouts and duration
```
If I am not mistaken, the error code 16 is for the macro `EBUSY`.
It’d be great, if the TPM would also be created in the newer Linux
Kernel versions, so that Debian users can upgrade to the upcoming stable
release, which ships Linux 4.9.
Unfortunately, I won’t be able to bisect the commit introducing the
regression. Could you please tell me how to debug, why the burstcount
cannot be read.
Kind regards,
Paul
[1] https://review.coreboot.org/13410/
