linux-kernel - [PATCH 4.9 017/164] tpm: add sleep only for retry in i2c_nuvoton_write

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Message-Id: <20170523200908.096001917@linuxfoundation.org>
Date:   Tue, 23 May 2017 22:07:14 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Nayna Jain <nayna@...ux.vnet.ibm.com>,
        Mimi Zohar <zohar@...ux.vnet.ibm.com>,
        Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
Subject: [PATCH 4.9 017/164] tpm: add sleep only for retry in i2c_nuvoton_write_status()

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Nayna Jain <nayna@...ux.vnet.ibm.com>

commit 0afb7118ae021e80ecf70f5a3336e0935505518a upstream.

Currently, there is an unnecessary 1 msec delay added in
i2c_nuvoton_write_status() for the successful case. This
function is called multiple times during send() and recv(),
which implies adding multiple extra delays for every TPM
operation.

This patch calls usleep_range() only if retry is to be done.

Signed-off-by: Nayna Jain <nayna@...ux.vnet.ibm.com>
Reviewed-by: Mimi Zohar <zohar@...ux.vnet.ibm.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/char/tpm/tpm_i2c_nuvoton.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

--- a/drivers/char/tpm/tpm_i2c_nuvoton.c
+++ b/drivers/char/tpm/tpm_i2c_nuvoton.c
@@ -124,8 +124,9 @@ static s32 i2c_nuvoton_write_status(stru
 	/* this causes the current command to be aborted */
 	for (i = 0, status = -1; i < TPM_I2C_RETRY_COUNT && status < 0; i++) {
 		status = i2c_nuvoton_write_buf(client, TPM_STS, 1, &data);
-		usleep_range(TPM_I2C_BUS_DELAY, TPM_I2C_BUS_DELAY
-			     + TPM_I2C_DELAY_RANGE);
+		if (status < 0)
+			usleep_range(TPM_I2C_BUS_DELAY, TPM_I2C_BUS_DELAY
+				     + TPM_I2C_DELAY_RANGE);
 	}
 	return status;
 }