linux-kernel - [PATCH v2 4/4] tpm: use tpm

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Date:   Wed,  6 Sep 2017 08:56:39 -0400
From:   Nayna Jain <nayna@...ux.vnet.ibm.com>
To:     tpmdd-devel@...ts.sourceforge.net
Cc:     peterhuewe@....de, tpmdd@...horst.net,
        jarkko.sakkinen@...ux.intel.com, jgunthorpe@...idianresearch.com,
        linux-security-module@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        linux-ima-devel@...ts.sourceforge.net, patrickc@...ibm.com,
        Nayna Jain <nayna@...ux.vnet.ibm.com>
Subject: [PATCH v2 4/4] tpm: use tpm_msleep() value as max delay

Currently, tpm_msleep() uses delay_msec as the minimum value in
usleep_range. However, that is the maximum time we want to wait.
The function is modified to use the delay_msec as the maximum
value, not the minimum value.

After this change, performance on a TPM 1.2 with an 8 byte
burstcount for 1000 extends improved from ~9sec to ~8sec.

Signed-off-by: Nayna Jain <nayna@...ux.vnet.ibm.com>
Acked-by: Mimi Zohar <zohar@...ux.vnet.ibm.com>
---
 drivers/char/tpm/tpm.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
index eb2f8818eded..ff5a8b7b80b9 100644
--- a/drivers/char/tpm/tpm.h
+++ b/drivers/char/tpm/tpm.h
@@ -533,8 +533,8 @@ int wait_for_tpm_stat(struct tpm_chip *chip, u8 mask, unsigned long timeout,
 
 static inline void tpm_msleep(unsigned int delay_msec)
 {
-	usleep_range(delay_msec * 1000,
-		     (delay_msec * 1000) + TPM_TIMEOUT_RANGE_US);
+	usleep_range((delay_msec * 1000) - TPM_TIMEOUT_RANGE_US,
+		     delay_msec * 1000);
 };
 
 struct tpm_chip *tpm_chip_find_get(int chip_num);
-- 
2.13.3