(Please CC me on replies - I'm not subscribed to LMKL) Prior to 0cf577a03f21 if a TPM 1.2 device was disabled, but visible (sysfs node "enabled" returns 0), creation of the TPM char device was only skipped if tpm_bios_log_setup returned -ENODEV.
On some systems like HP DL380 G9, if the TPM is disabled but visible, the TCPA log is empty, which means tpm_read_log_acpi returns -EIO. Starting with 0cf577a03f21, -EIO triggers an early return from tpm_chip_register which means the char device is not created. Log snippet: [ 4.320387] tpm_tis 00:00: 1.2 TPM (device-id 0xB, rev-id 16) [ 4.455389] tpm tpm0: A TPM error (7) occurred attempting to read a pcr value [ 4.457762] tpm tpm0: TPM is disabled/deactivated (0x7) [ 4.459461] tpm tpm0: tpm_read_log_acpi: TCPA log area empty <---------------------- [ 4.461312] tpm_tis: probe of 00:00 failed with error -5 Thanks, Sahil
