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Subject[PATCH v2 2/4] tpm: define __wait_for_tpm_stat to specify variable polling sleep time
Date
The existing wait_for_tpm_stat() checks the chip status before
sleeping for 5 msec in a polling loop. For some functions although
the status isn't ready immediately, the status returns extremely
quickly. Waiting for 5 msec causes an unnecessary delay. An
example is the send() call in the tpms_tis driver.

This patch defines __wait_for_tpm_stat(), allowing the caller
to specify the polling sleep timeout value within the loop.
The existing wait_for_tpm_stat() becomes a wrapper for this
function.

After this change, performance on a TPM 1.2 with an 8 byte
burstcount for 1000 extends improved from ~14sec to ~10sec.

Signed-off-by: Nayna Jain <nayna@linux.vnet.ibm.com>
Acked-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
---
drivers/char/tpm/tpm-interface.c | 15 ++++++++++++---
drivers/char/tpm/tpm.h | 3 +++
drivers/char/tpm/tpm_tis_core.c | 11 ++++++-----
3 files changed, 21 insertions(+), 8 deletions(-)

diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
index 1d6729be4cd6..b23d006243b7 100644
--- a/drivers/char/tpm/tpm-interface.c
+++ b/drivers/char/tpm/tpm-interface.c
@@ -1050,8 +1050,9 @@ static bool wait_for_tpm_stat_cond(struct tpm_chip *chip, u8 mask,
return false;
}

-int wait_for_tpm_stat(struct tpm_chip *chip, u8 mask, unsigned long timeout,
- wait_queue_head_t *queue, bool check_cancel)
+int __wait_for_tpm_stat(struct tpm_chip *chip, u8 mask, unsigned long timeout,
+ unsigned int poll_sleep, wait_queue_head_t *queue,
+ bool check_cancel)
{
unsigned long stop;
long rc;
@@ -1085,7 +1086,7 @@ int wait_for_tpm_stat(struct tpm_chip *chip, u8 mask, unsigned long timeout,
}
} else {
do {
- tpm_msleep(TPM_TIMEOUT);
+ tpm_msleep(poll_sleep);
status = chip->ops->status(chip);
if ((status & mask) == mask)
return 0;
@@ -1093,6 +1094,14 @@ int wait_for_tpm_stat(struct tpm_chip *chip, u8 mask, unsigned long timeout,
}
return -ETIME;
}
+EXPORT_SYMBOL_GPL(__wait_for_tpm_stat);
+
+int wait_for_tpm_stat(struct tpm_chip *chip, u8 mask, unsigned long timeout,
+ wait_queue_head_t *queue, bool check_cancel)
+{
+ return __wait_for_tpm_stat(chip, mask, timeout, TPM_TIMEOUT,
+ queue, check_cancel);
+}
EXPORT_SYMBOL_GPL(wait_for_tpm_stat);

#define TPM_ORD_SAVESTATE 152
diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
index 2d5466a72e40..eb2f8818eded 100644
--- a/drivers/char/tpm/tpm.h
+++ b/drivers/char/tpm/tpm.h
@@ -525,6 +525,9 @@ int tpm_do_selftest(struct tpm_chip *chip);
unsigned long tpm_calc_ordinal_duration(struct tpm_chip *chip, u32 ordinal);
int tpm_pm_suspend(struct device *dev);
int tpm_pm_resume(struct device *dev);
+int __wait_for_tpm_stat(struct tpm_chip *chip, u8 mask,
+ unsigned long timeout, unsigned int poll_sleep,
+ wait_queue_head_t *queue, bool check_cancel);
int wait_for_tpm_stat(struct tpm_chip *chip, u8 mask, unsigned long timeout,
wait_queue_head_t *queue, bool check_cancel);

diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
index 6b9bf4c4d434..d1eab29cb447 100644
--- a/drivers/char/tpm/tpm_tis_core.c
+++ b/drivers/char/tpm/tpm_tis_core.c
@@ -268,8 +268,8 @@ static int tpm_tis_send_data(struct tpm_chip *chip, u8 *buf, size_t len)
status = tpm_tis_status(chip);
if ((status & TPM_STS_COMMAND_READY) == 0) {
tpm_tis_ready(chip);
- if (wait_for_tpm_stat
- (chip, TPM_STS_COMMAND_READY, chip->timeout_b,
+ if (__wait_for_tpm_stat
+ (chip, TPM_STS_COMMAND_READY, chip->timeout_b, 1,
&priv->int_queue, false) < 0) {
rc = -ETIME;
goto out_err;
@@ -303,7 +303,8 @@ static int tpm_tis_send_data(struct tpm_chip *chip, u8 *buf, size_t len)
if (ignore_burst_count)
continue;

- if (wait_for_tpm_stat(chip, TPM_STS_VALID, chip->timeout_c,
+ if (__wait_for_tpm_stat(chip, TPM_STS_VALID,
+ chip->timeout_c, 1,
&priv->int_queue, false) < 0) {
rc = -ETIME;
goto out_err;
@@ -320,8 +321,8 @@ static int tpm_tis_send_data(struct tpm_chip *chip, u8 *buf, size_t len)
if (rc < 0)
goto out_err;

- if (wait_for_tpm_stat(chip, TPM_STS_VALID, chip->timeout_c,
- &priv->int_queue, false) < 0) {
+ if (__wait_for_tpm_stat(chip, TPM_STS_VALID, chip->timeout_c,
+ 1, &priv->int_queue, false) < 0) {
rc = -ETIME;
goto out_err;
}
--
2.13.3
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