On Thu, Oct 01, 2026 at 08:01:11AM +0200, A. Sverdlin wrote: > From: Alexander Sverdlin <[email protected]> > > tpm2_probe() reads the protocol version from the response tag and is > documented to return -errno on failure, but it always returns 0. A > transport error (tpm_transmit_cmd() < 0) is thus swallowed together with > the intentionally ignored TPM response code, leaving TPM_CHIP_FLAG_TPM2 > unset. A transient bus failure on the first command then misdetects a > TPM 2.0 as a 1.2 and the probe fails on the TPM 1.2 path: > > tpm_tis_i2c 0-002e: 1.2 TPM (device-id 0x1C, rev-id 22) > tpm tpm0: A TPM error (-62) occurred attempting to determine the timeouts > > Return the transport error instead; rc >= 0 still means a valid header was > received and the TPM's own response code is still ignored. > > Fixes: 94e266ba1fa3 ("tpm: migrate tpm2_probe() to use struct tpm_buf") > Cc: [email protected] > Signed-off-by: Alexander Sverdlin <[email protected]> > --- > drivers/char/tpm/tpm2-cmd.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c > index a94f4395c198a..4b2bb2ddc321a 100644 > --- a/drivers/char/tpm/tpm2-cmd.c > +++ b/drivers/char/tpm/tpm2-cmd.c > @@ -483,8 +483,9 @@ int tpm2_probe(struct tpm_chip *chip) > out = (struct tpm_header *)buf->data; > if (be16_to_cpu(out->tag) == TPM2_ST_NO_SESSIONS) > chip->flags |= TPM_CHIP_FLAG_TPM2; > + return 0; > } > - return 0; > + return rc; > } > EXPORT_SYMBOL_GPL(tpm2_probe); > > -- > 2.55.0 >
Reviewed-by: Jarkko Sakkinen <[email protected]> Thanks. Br, Jarkko
