tpm: reduce poll sleep time in tpm_transmit()

tpm_try_transmit currently checks TPM status every 5 msecs between
send and recv. It does so in a loop for the maximum timeout as defined
in the TPM Interface Specification. However, the TPM may return before
5 msecs. Thus the polling interval for each iteration can be reduced,
which improves overall performance. This patch changes the polling sleep
time from 5 msecs to 1 msec.

Additionally, this patch renames TPM_POLL_SLEEP to TPM_TIMEOUT_POLL and
moves it to tpm.h as an enum value.

After this change, performance on a system[1] with a TPM 1.2 with an 8 byte
burstcount for 1000 extends improved from ~14 sec to ~10.7 sec.

[1] All tests are performed on an x86 based, locked down, single purpose
closed system. It has Infineon TPM 1.2 using LPC Bus.

Signed-off-by: Nayna Jain <nayna@linux.vnet.ibm.com>
Acked-by: Jay Freyensee <why2jjj.linux@gmail.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>

diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
index 6201aab374e6ac35da76bb57c1a54cbe860bc1ac..e32f6e85dc6d0658b3ad61339c65b0dff9738c75 100644 (file)
--- a/drivers/char/tpm/tpm-interface.c
+++ b/drivers/char/tpm/tpm-interface.c
@@ -489,7 +489,7 @@ static ssize_t tpm_try_transmit(struct tpm_chip *chip,
                        goto out;
                }
 
-               tpm_msleep(TPM_TIMEOUT);
+               tpm_msleep(TPM_TIMEOUT_POLL);
                rmb();
        } while (time_before(jiffies, stop));
 

diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
index af3bb87d3ea1e07a5dc621246a26f111f53557c8..baa066997372678a6eb01ec7fc0658c6f60c2a91 100644 (file)
--- a/drivers/char/tpm/tpm.h
+++ b/drivers/char/tpm/tpm.h
@@ -53,7 +53,8 @@ enum tpm_const {
 enum tpm_timeout {
        TPM_TIMEOUT = 5,        /* msecs */
        TPM_TIMEOUT_RETRY = 100, /* msecs */
-       TPM_TIMEOUT_RANGE_US = 300      /* usecs */
+       TPM_TIMEOUT_RANGE_US = 300,     /* usecs */
+       TPM_TIMEOUT_POLL = 1    /* msecs */
 };
 
 /* TPM addresses */

diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
index d547cd309dbdf2ea16ba0fea5a8f58fdd600ff2d..7bfdec66be447c3dcb232f843f776ae323475eb3 100644 (file)
--- a/drivers/char/tpm/tpm_tis_core.c
+++ b/drivers/char/tpm/tpm_tis_core.c
@@ -31,12 +31,6 @@
 #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 void tpm_tis_clkrun_enable(struct tpm_chip *chip, bool value);
 
 static bool wait_for_tpm_stat_cond(struct tpm_chip *chip, u8 mask,
@@ -90,7 +84,7 @@ again:
                }
        } else {
                do {
-                       tpm_msleep(TPM_POLL_SLEEP);
+                       tpm_msleep(TPM_TIMEOUT_POLL);
                        status = chip->ops->status(chip);
                        if ((status & mask) == mask)
                                return 0;
@@ -279,7 +273,7 @@ static int get_burstcount(struct tpm_chip *chip)
                burstcnt = (value >> 8) & 0xFFFF;
                if (burstcnt)
                        return burstcnt;
-               tpm_msleep(TPM_POLL_SLEEP);
+               tpm_msleep(TPM_TIMEOUT_POLL);
        } while (time_before(jiffies, stop));
        return -EBUSY;
 }