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authorNayna Jain <nayna@linux.vnet.ibm.com>2017-10-17 16:32:31 -0400
committerJarkko Sakkinen <jarkko.sakkinen@linux.intel.com>2018-01-08 12:58:33 +0200
commitcf151a9a44d52a63332e8e926234574fe5a5d784 (patch)
treecbc70f536e73009213eaec0915cbb1510e464f7c /drivers/char
parent87cdfdd19aefcf639507ce96ae8f403539a8ba29 (diff)
tpm: reduce tpm polling delay in tpm_tis_core
The existing wait_for_tpm_stat() polls for the chip status after 5msec sleep. As per TCG ddwg input, it is expected that tpm might return status in few usec. So, reducing the delay in polling to 1msec. Similarly, get_burstcount() function sleeps for 5msec before retrying for next query to burstcount in a loop. If it takes lesser time for TPM to return, this 5msec delay is longer than necessary. After this change, performance on a TPM 1.2 with an 8 byte burstcount for 1000 extends improved from ~14sec to ~9sec. Signed-off-by: Nayna Jain <nayna@linux.vnet.ibm.com> Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> Tested-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Diffstat (limited to 'drivers/char')
-rw-r--r--drivers/char/tpm/tpm_tis_core.c10
1 files changed, 8 insertions, 2 deletions
diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
index 9e96b4b66aee..ca6b2b527d52 100644
--- a/drivers/char/tpm/tpm_tis_core.c
+++ b/drivers/char/tpm/tpm_tis_core.c
@@ -31,6 +31,12 @@
#include "tpm.h"
#include "tpm_tis_core.h"
+/* This is a polling delay to check for status and burstcount.
+ * As per ddwg input, expectation is that status check and burstcount
+ * check should return within few usecs.
+ */
+#define TPM_POLL_SLEEP 1 /* msec */
+
static bool wait_for_tpm_stat_cond(struct tpm_chip *chip, u8 mask,
bool check_cancel, bool *canceled)
{
@@ -82,7 +88,7 @@ again:
}
} else {
do {
- tpm_msleep(TPM_TIMEOUT);
+ tpm_msleep(TPM_POLL_SLEEP);
status = chip->ops->status(chip);
if ((status & mask) == mask)
return 0;
@@ -224,7 +230,7 @@ static int get_burstcount(struct tpm_chip *chip)
burstcnt = (value >> 8) & 0xFFFF;
if (burstcnt)
return burstcnt;
- tpm_msleep(TPM_TIMEOUT);
+ tpm_msleep(TPM_POLL_SLEEP);
} while (time_before(jiffies, stop));
return -EBUSY;
}