Hi, I have integrated the TPM 2.0 Iridium SLB 9670 together with the i.MX8MP processor to implement remote attestation using the IMA Linux kernel module. Sometimes I get strange this error "tpm tpm0: invalid TPM_STS.x 0xa8 " that I cannot find a solution online. As I understand it I should get 0xff in case there are transmission calls to tpm that are not protected by the tpm_try_get_ops command. Checking the Linux kernel however it is indeed called and in fact, the value is not 0xff but is variable. On a couple of other occasions, however, it has failed to even establish the initial connection ('2.0 TPM (device-id 0x1B, rev-id 22') and some debugging showed that the tpm spi driver was stuck in an infinite loop waiting for the TPM locality. The wiring is correct, in fact, if the tpm connects without errors, the tpm2tools commands work. The device tree is correct because I asked for confirmation on the NXP forum. I also tried replacing the tpm but got the same result. I currently I'm using Linux kernel 5.15.60 but I get the same error using the i.MX6UL board which has kernel 5.10.60. What caused this error?
The output of dmesg | grep -i tpm
[ 2.077539] tpm_tis_spi spi1.0: 2.0 TPM (device-id 0x1B, rev-id 22)
[ 2.088911] tpm tpm0: A TPM error (256) occurred attempting the self test
[ 2.095719] tpm tpm0: starting up the TPM manually
[ 12.489312] tpm tpm0: tpm_try_transmit: send(): error -5
[ 38.235405] tpm tpm0: tpm_transmit: tpm_recv: error -52
[ 38.284794] tpm tpm0: invalid TPM_STS.x 0x85, dumping stack for forensics
[ 38.284861] tpm_tis_status+0xc8/0xe4
[ 38.284869] wait_for_tpm_stat+0x54/0x224
[ 38.284878] tpm_tis_send_data+0x220/0x28c
[ 38.284886] tpm_tis_send_main+0x34/0x110
[ 38.284893] tpm_tis_send+0x44/0x110
[ 38.284901] tpm_transmit+0xc8/0x340
[ 38.284908] tpm_transmit_cmd+0x30/0xc0
[ 38.284914] tpm2_pcr_extend+0x25c/0x300
[ 38.284921] tpm_pcr_extend+0xc4/0xd4
