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-rw-r--r--src/drivers/pc80/tpm/Kconfig9
-rw-r--r--src/drivers/pc80/tpm/tis.c8
2 files changed, 17 insertions, 0 deletions
diff --git a/src/drivers/pc80/tpm/Kconfig b/src/drivers/pc80/tpm/Kconfig
index 3bd9083802..879b4a2341 100644
--- a/src/drivers/pc80/tpm/Kconfig
+++ b/src/drivers/pc80/tpm/Kconfig
@@ -46,3 +46,12 @@ config TPM_DEACTIVATE
depends on LPC_TPM
help
Deactivate TPM by issuing deactivate command.
+
+config TPM_RDRESP_NEED_DELAY
+ bool "Enable Delay Workaround for TPM"
+ default n
+ depends on LPC_TPM
+ help
+ Certain TPMs seem to need some delay when reading response
+ to work around a race-condition-related issue, possibly
+ caused by ill-programmed TPM firmware.
diff --git a/src/drivers/pc80/tpm/tis.c b/src/drivers/pc80/tpm/tis.c
index 9802654ee1..714b7e5ed0 100644
--- a/src/drivers/pc80/tpm/tis.c
+++ b/src/drivers/pc80/tpm/tis.c
@@ -595,6 +595,14 @@ static u32 tis_readresponse(u8 *buffer, size_t *len)
if (offset == expected_count)
break; /* We got all we need */
+ /*
+ * Certain TPMs seem to need some delay between tis_wait_valid()
+ * and tis_has_valid_data(), or some race-condition-related
+ * issue will occur.
+ */
+ if (IS_ENABLED(CONFIG_TPM_RDRESP_NEED_DELAY))
+ udelay(10);
+
} while (tis_has_valid_data(locality));
/* * Make sure we indeed read all there was. */