tpm_tis_core: Choose appropriate timeout for reading burstcount
authorAlexander Steffen <Alexander.Steffen@infineon.com>
Thu, 16 Feb 2017 15:33:36 +0000 (15:33 +0000)
committerJarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Mon, 3 Apr 2017 19:46:00 +0000 (22:46 +0300)
commit302a6ad7fc77146191126a1f3e2c5d724fd72416
treee7ef7a74c31397af36adc955176e3b1b298c87c9
parentddb99e118e37f324a4be65a411bb60ae62795cf9
tpm_tis_core: Choose appropriate timeout for reading burstcount

TIS v1.3 for TPM 1.2 and PTP for TPM 2.0 disagree about which timeout
value applies to reading a valid burstcount. It is TIMEOUT_D according to
TIS, but TIMEOUT_A according to PTP, so choose the appropriate value
depending on whether we deal with a TPM 1.2 or a TPM 2.0.

This is important since according to the PTP TIMEOUT_D is much smaller
than TIMEOUT_A. So the previous implementation could run into timeouts
with a TPM 2.0, even though the TPM was behaving perfectly fine.

During tpm2_probe TIMEOUT_D will be used even with a TPM 2.0, because
TPM_CHIP_FLAG_TPM2 is not yet set. This is fine, since the timeout values
will only be changed afterwards by tpm_get_timeouts. Until then
TIS_TIMEOUT_D_MAX applies, which is large enough.

Cc: stable@vger.kernel.org
Fixes: aec04cbdf723 ("tpm: TPM 2.0 FIFO Interface")

Signed-off-by: Alexander Steffen <Alexander.Steffen@infineon.com>
Signed-off-by: Peter Huewe <peter.huewe@infineon.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
drivers/char/tpm/tpm_tis_core.c