[PATCH v3] tpm: tis: Double the timeout B to 4s

[Michal Suchanek]

With some Infineon chips the timeouts in tpm_tis_send_data (both B and
C) can reach up to about 2250 ms.

Timeout C is retried since
commit de9e33df7762 ("tpm, tpm_tis: Workaround failed command reception on Infineon devices")

Timeout B still needs to be extended.

The problem is most commonly encountered with context related operation
such as load context/save context. These are issued directly by the
kernel, and there is no retry logic for them.

When a filesystem is set up to use the TPM for unlocking the boot fails,
and restarting the userspace service is ineffective. This is likely
because ignoring a load context/save context result puts the real TPM
state and the TPM state expected by the kernel out of sync.

Chips known to be affected:
tpm_tis IFX1522:00: 2.0 TPM (device-id 0x1D, rev-id 54)
Description: SLB9672
Firmware Revision: 15.22

tpm_tis MSFT0101:00: 2.0 TPM (device-id 0x1B, rev-id 22)
Firmware Revision: 7.83

tpm_tis MSFT0101:00: 2.0 TPM (device-id 0x1A, rev-id 16)
Firmware Revision: 5.63

Link: https://lore.kernel.org/linux-integrity/Z5pI07m0Muapyu9w@xxxxxxxxxxxxxxx/
Signed-off-by: Michal Suchanek <msuchanek@xxxxxxx>
---
v2: Only extend timeout B
v3: Update commit message
---
 drivers/char/tpm/tpm_tis_core.h | 2 +-
 include/linux/tpm.h             | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/char/tpm/tpm_tis_core.h b/drivers/char/tpm/tpm_tis_core.h
index 970d02c337c7..6c3aa480396b 100644
--- a/drivers/char/tpm/tpm_tis_core.h
+++ b/drivers/char/tpm/tpm_tis_core.h
@@ -54,7 +54,7 @@ enum tis_int_flags {
 enum tis_defaults {
 	TIS_MEM_LEN = 0x5000,
 	TIS_SHORT_TIMEOUT = 750,	/* ms */
-	TIS_LONG_TIMEOUT = 2000,	/* 2 sec */
+	TIS_LONG_TIMEOUT = 4000,	/* 4 secs */
 	TIS_TIMEOUT_MIN_ATML = 14700,	/* usecs */
 	TIS_TIMEOUT_MAX_ATML = 15000,	/* usecs */
 };
diff --git a/include/linux/tpm.h b/include/linux/tpm.h
index 6c3125300c00..3db0b6a87d45 100644
--- a/include/linux/tpm.h
+++ b/include/linux/tpm.h
@@ -224,7 +224,7 @@ enum tpm2_const {
 
 enum tpm2_timeouts {
 	TPM2_TIMEOUT_A          =    750,
-	TPM2_TIMEOUT_B          =   2000,
+	TPM2_TIMEOUT_B          =   4000,
 	TPM2_TIMEOUT_C          =    200,
 	TPM2_TIMEOUT_D          =     30,
 	TPM2_DURATION_SHORT     =     20,
-- 
2.47.1