* [PATCH v4 0/2] tpm: improving granularity in poll sleep times
@ 2018-05-16 5:51 ` Nayna Jain
0 siblings, 0 replies; 9+ messages in thread
From: Nayna Jain @ 2018-05-16 5:51 UTC (permalink / raw)
To: linux-security-module
The existing TPM polling code sleeps in each loop iteration for time in
msecs ranging from 1 msecs to 5 msecs. However, many of the TPM commands
complete much faster, resulting in unnecessary delays.
This set of patches identifies such iterations and optimizes the sleep
time. The first patch replaces TPM_POLL_SLEEP with TPM_TIMEOUT_POLL and
moves it from tpm_tis_core.c to tpm.h as an enum with value 1 msecs. The
second patch further reduces the TPM poll sleep time in get_burstcount()
and wait_for_tpm_stat() in tpm_tis_core.c by calling usleep_range()
directly.
The change is only in the polling time, and the maximum timeout is still
maintained the same. Thus, it should not affect the overall existing
behavior.
Changelog:
v4:
tpm: reduce poll sleep time in tpm_transmit()
* added Reviewed-by, Tested-by and Ack-by
tpm: reduce polling time to usecs for even finer granularity
* included Jarkko's feedback
* added Ack-by
v3:
tpm: reduce poll sleep time in tpm_transmit()
* added testing platform information
* updated patch description for more clarity on reasoning
tpm: reduce polling time to usecs for even finer granularity
* added testing platform information
* added Jarkko's and Mimi's Reviewed-by
v2:
tpm: reduce poll sleep time in tpm_transmit()
* merged previously defined two patches into this.
* updated patch description as per Jarkko's feedback
tpm: reduce polling time to usecs for even finer granularity
* directly use usleep_range with finer granularity less than 1msec
Nayna Jain (2):
tpm: reduce poll sleep time in tpm_transmit()
tpm: reduce polling time to usecs for even finer granularity
drivers/char/tpm/tpm-interface.c | 2 +-
drivers/char/tpm/tpm.h | 5 ++++-
drivers/char/tpm/tpm_tis_core.c | 11 +++--------
3 files changed, 8 insertions(+), 10 deletions(-)
--
2.13.3
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^ permalink raw reply [flat|nested] 9+ messages in thread
* [PATCH v4 1/2] tpm: reduce poll sleep time in tpm_transmit()
2018-05-16 5:51 ` Nayna Jain
@ 2018-05-16 5:51 ` Nayna Jain
-1 siblings, 0 replies; 9+ messages in thread
From: Nayna Jain @ 2018-05-16 5:51 UTC (permalink / raw)
To: linux-integrity
Cc: zohar, linux-security-module, linux-kernel, peterhuewe,
jarkko.sakkinen, tpmdd, jgunthorpe, patrickc, Nayna Jain
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>
Reviewed-by: Mimi Zohar <zohar@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>
---
drivers/char/tpm/tpm-interface.c | 2 +-
drivers/char/tpm/tpm.h | 3 ++-
drivers/char/tpm/tpm_tis_core.c | 10 ++--------
3 files changed, 5 insertions(+), 10 deletions(-)
diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
index 9e80a953d693..a676d8ad5992 100644
--- a/drivers/char/tpm/tpm-interface.c
+++ b/drivers/char/tpm/tpm-interface.c
@@ -470,7 +470,7 @@ ssize_t tpm_transmit(struct tpm_chip *chip, struct tpm_space *space,
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 f895fba4e20d..7e797377e1eb 100644
--- 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 da074e3db19b..021e6b68f2db 100644
--- 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 @@ static int wait_for_tpm_stat(struct tpm_chip *chip, u8 mask,
}
} else {
do {
- tpm_msleep(TPM_POLL_SLEEP);
+ tpm_msleep(TPM_TIMEOUT_POLL);
status = chip->ops->status(chip);
if ((status & mask) == mask)
return 0;
@@ -232,7 +226,7 @@ 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;
}
--
2.13.3
^ permalink raw reply related [flat|nested] 9+ messages in thread* [PATCH v4 1/2] tpm: reduce poll sleep time in tpm_transmit()
@ 2018-05-16 5:51 ` Nayna Jain
0 siblings, 0 replies; 9+ messages in thread
From: Nayna Jain @ 2018-05-16 5:51 UTC (permalink / raw)
To: linux-security-module
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>
Reviewed-by: Mimi Zohar <zohar@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>
---
drivers/char/tpm/tpm-interface.c | 2 +-
drivers/char/tpm/tpm.h | 3 ++-
drivers/char/tpm/tpm_tis_core.c | 10 ++--------
3 files changed, 5 insertions(+), 10 deletions(-)
diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
index 9e80a953d693..a676d8ad5992 100644
--- a/drivers/char/tpm/tpm-interface.c
+++ b/drivers/char/tpm/tpm-interface.c
@@ -470,7 +470,7 @@ ssize_t tpm_transmit(struct tpm_chip *chip, struct tpm_space *space,
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 f895fba4e20d..7e797377e1eb 100644
--- 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 da074e3db19b..021e6b68f2db 100644
--- 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 @@ static int wait_for_tpm_stat(struct tpm_chip *chip, u8 mask,
}
} else {
do {
- tpm_msleep(TPM_POLL_SLEEP);
+ tpm_msleep(TPM_TIMEOUT_POLL);
status = chip->ops->status(chip);
if ((status & mask) == mask)
return 0;
@@ -232,7 +226,7 @@ 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;
}
--
2.13.3
--
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^ permalink raw reply related [flat|nested] 9+ messages in thread* Re: [PATCH v4 1/2] tpm: reduce poll sleep time in tpm_transmit()
2018-05-16 5:51 ` Nayna Jain
@ 2018-05-16 14:10 ` Jarkko Sakkinen
-1 siblings, 0 replies; 9+ messages in thread
From: Jarkko Sakkinen @ 2018-05-16 14:10 UTC (permalink / raw)
To: Nayna Jain
Cc: linux-integrity, zohar, linux-security-module, linux-kernel,
peterhuewe, tpmdd, jgunthorpe, patrickc
On Wed, May 16, 2018 at 01:51:24AM -0400, Nayna Jain wrote:
> 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.
Already applied previous version of this.
/Jarkko
^ permalink raw reply [flat|nested] 9+ messages in thread
* [PATCH v4 1/2] tpm: reduce poll sleep time in tpm_transmit()
@ 2018-05-16 14:10 ` Jarkko Sakkinen
0 siblings, 0 replies; 9+ messages in thread
From: Jarkko Sakkinen @ 2018-05-16 14:10 UTC (permalink / raw)
To: linux-security-module
On Wed, May 16, 2018 at 01:51:24AM -0400, Nayna Jain wrote:
> 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.
Already applied previous version of this.
/Jarkko
--
To unsubscribe from this list: send the line "unsubscribe linux-security-module" in
the body of a message to majordomo at vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
^ permalink raw reply [flat|nested] 9+ messages in thread
* [PATCH v4 2/2] tpm: reduce polling time to usecs for even finer granularity
2018-05-16 5:51 ` Nayna Jain
(?)
@ 2018-05-16 5:51 ` Nayna Jain
-1 siblings, 0 replies; 9+ messages in thread
From: Nayna Jain @ 2018-05-16 5:51 UTC (permalink / raw)
To: linux-integrity
Cc: zohar, linux-security-module, linux-kernel, peterhuewe,
jarkko.sakkinen, tpmdd, jgunthorpe, patrickc, Nayna Jain
The TPM burstcount and status commands are supposed to return very
quickly [2][3]. This patch further reduces the TPM poll sleep time to usecs
in get_burstcount() and wait_for_tpm_stat() by calling usleep_range()
directly.
After this change, performance on a system[1] with a TPM 1.2 with an 8 byte
burstcount for 1000 extends improved from ~10.7 sec to ~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.
[2] From the TCG Specification "TCG PC Client Specific TPM Interface
Specification (TIS), Family 1.2":
"NOTE : It takes roughly 330 ns per byte transfer on LPC. 256 bytes would
take 84 us, which is a long time to stall the CPU. Chipsets may not be
designed to post this much data to LPC; therefore, the CPU itself is
stalled for much of this time. Sending 1 kB would take 350 μs. Therefore,
even if the TPM_STS_x.burstCount field is a high value, software SHOULD
be interruptible during this period."
[3] From the TCG Specification 2.0, "TCG PC Client Platform TPM Profile
(PTP) Specification":
"It takes roughly 330 ns per byte transfer on LPC. 256 bytes would take
84 us. Chipsets may not be designed to post this much data to LPC;
therefore, the CPU itself is stalled for much of this time. Sending 1 kB
would take 350 us. Therefore, even if the TPM_STS_x.burstCount field is a
high value, software should be interruptible during this period. For SPI,
assuming 20MHz clock and 64-byte transfers, it would take about 120 usec
to move 256B of data. Sending 1kB would take about 500 usec. If the
transactions are done using 4 bytes at a time, then it would take about
1 msec. to transfer 1kB of data."
Signed-off-by: Nayna Jain <nayna@linux.vnet.ibm.com>
Reviewed-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Acked-by: Jay Freyensee <why2jjj.linux@gmail.com>
---
drivers/char/tpm/tpm.h | 4 +++-
drivers/char/tpm/tpm_tis_core.c | 5 +++--
2 files changed, 6 insertions(+), 3 deletions(-)
diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
index 7e797377e1eb..f0e4d290c347 100644
--- a/drivers/char/tpm/tpm.h
+++ b/drivers/char/tpm/tpm.h
@@ -54,7 +54,9 @@ enum tpm_timeout {
TPM_TIMEOUT = 5, /* msecs */
TPM_TIMEOUT_RETRY = 100, /* msecs */
TPM_TIMEOUT_RANGE_US = 300, /* usecs */
- TPM_TIMEOUT_POLL = 1 /* msecs */
+ TPM_TIMEOUT_POLL = 1, /* msecs */
+ TPM_TIMEOUT_USECS_MIN = 100, /* usecs */
+ TPM_TIMEOUT_USECS_MAX = 500 /* usecs */
};
/* TPM addresses */
diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
index 021e6b68f2db..bbd8eed30e57 100644
--- a/drivers/char/tpm/tpm_tis_core.c
+++ b/drivers/char/tpm/tpm_tis_core.c
@@ -84,7 +84,8 @@ static int wait_for_tpm_stat(struct tpm_chip *chip, u8 mask,
}
} else {
do {
- tpm_msleep(TPM_TIMEOUT_POLL);
+ usleep_range(TPM_TIMEOUT_USECS_MIN,
+ TPM_TIMEOUT_USECS_MAX);
status = chip->ops->status(chip);
if ((status & mask) == mask)
return 0;
@@ -226,7 +227,7 @@ static int get_burstcount(struct tpm_chip *chip)
burstcnt = (value >> 8) & 0xFFFF;
if (burstcnt)
return burstcnt;
- tpm_msleep(TPM_TIMEOUT_POLL);
+ usleep_range(TPM_TIMEOUT_USECS_MIN, TPM_TIMEOUT_USECS_MAX);
} while (time_before(jiffies, stop));
return -EBUSY;
}
--
2.13.3
^ permalink raw reply related [flat|nested] 9+ messages in thread* [PATCH v4 2/2] tpm: reduce polling time to usecs for even finer granularity
@ 2018-05-16 5:51 ` Nayna Jain
0 siblings, 0 replies; 9+ messages in thread
From: Nayna Jain @ 2018-05-16 5:51 UTC (permalink / raw)
To: linux-integrity
Cc: zohar, linux-security-module, linux-kernel, peterhuewe,
jarkko.sakkinen, tpmdd, jgunthorpe, patrickc, Nayna Jain
The TPM burstcount and status commands are supposed to return very
quickly [2][3]. This patch further reduces the TPM poll sleep time to usecs
in get_burstcount() and wait_for_tpm_stat() by calling usleep_range()
directly.
After this change, performance on a system[1] with a TPM 1.2 with an 8 byte
burstcount for 1000 extends improved from ~10.7 sec to ~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.
[2] From the TCG Specification "TCG PC Client Specific TPM Interface
Specification (TIS), Family 1.2":
"NOTE : It takes roughly 330 ns per byte transfer on LPC. 256 bytes would
take 84 us, which is a long time to stall the CPU. Chipsets may not be
designed to post this much data to LPC; therefore, the CPU itself is
stalled for much of this time. Sending 1 kB would take 350 us. Therefore,
even if the TPM_STS_x.burstCount field is a high value, software SHOULD
be interruptible during this period."
[3] From the TCG Specification 2.0, "TCG PC Client Platform TPM Profile
(PTP) Specification":
"It takes roughly 330 ns per byte transfer on LPC. 256 bytes would take
84 us. Chipsets may not be designed to post this much data to LPC;
therefore, the CPU itself is stalled for much of this time. Sending 1 kB
would take 350 us. Therefore, even if the TPM_STS_x.burstCount field is a
high value, software should be interruptible during this period. For SPI,
assuming 20MHz clock and 64-byte transfers, it would take about 120 usec
to move 256B of data. Sending 1kB would take about 500 usec. If the
transactions are done using 4 bytes at a time, then it would take about
1 msec. to transfer 1kB of data."
Signed-off-by: Nayna Jain <nayna@linux.vnet.ibm.com>
Reviewed-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Acked-by: Jay Freyensee <why2jjj.linux@gmail.com>
---
drivers/char/tpm/tpm.h | 4 +++-
drivers/char/tpm/tpm_tis_core.c | 5 +++--
2 files changed, 6 insertions(+), 3 deletions(-)
diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
index 7e797377e1eb..f0e4d290c347 100644
--- a/drivers/char/tpm/tpm.h
+++ b/drivers/char/tpm/tpm.h
@@ -54,7 +54,9 @@ enum tpm_timeout {
TPM_TIMEOUT = 5, /* msecs */
TPM_TIMEOUT_RETRY = 100, /* msecs */
TPM_TIMEOUT_RANGE_US = 300, /* usecs */
- TPM_TIMEOUT_POLL = 1 /* msecs */
+ TPM_TIMEOUT_POLL = 1, /* msecs */
+ TPM_TIMEOUT_USECS_MIN = 100, /* usecs */
+ TPM_TIMEOUT_USECS_MAX = 500 /* usecs */
};
/* TPM addresses */
diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
index 021e6b68f2db..bbd8eed30e57 100644
--- a/drivers/char/tpm/tpm_tis_core.c
+++ b/drivers/char/tpm/tpm_tis_core.c
@@ -84,7 +84,8 @@ static int wait_for_tpm_stat(struct tpm_chip *chip, u8 mask,
}
} else {
do {
- tpm_msleep(TPM_TIMEOUT_POLL);
+ usleep_range(TPM_TIMEOUT_USECS_MIN,
+ TPM_TIMEOUT_USECS_MAX);
status = chip->ops->status(chip);
if ((status & mask) == mask)
return 0;
@@ -226,7 +227,7 @@ static int get_burstcount(struct tpm_chip *chip)
burstcnt = (value >> 8) & 0xFFFF;
if (burstcnt)
return burstcnt;
- tpm_msleep(TPM_TIMEOUT_POLL);
+ usleep_range(TPM_TIMEOUT_USECS_MIN, TPM_TIMEOUT_USECS_MAX);
} while (time_before(jiffies, stop));
return -EBUSY;
}
--
2.13.3
^ permalink raw reply related [flat|nested] 9+ messages in thread* [PATCH v4 2/2] tpm: reduce polling time to usecs for even finer granularity
@ 2018-05-16 5:51 ` Nayna Jain
0 siblings, 0 replies; 9+ messages in thread
From: Nayna Jain @ 2018-05-16 5:51 UTC (permalink / raw)
To: linux-security-module
The TPM burstcount and status commands are supposed to return very
quickly [2][3]. This patch further reduces the TPM poll sleep time to usecs
in get_burstcount() and wait_for_tpm_stat() by calling usleep_range()
directly.
After this change, performance on a system[1] with a TPM 1.2 with an 8 byte
burstcount for 1000 extends improved from ~10.7 sec to ~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.
[2] From the TCG Specification "TCG PC Client Specific TPM Interface
Specification (TIS), Family 1.2":
"NOTE : It takes roughly 330 ns per byte transfer on LPC. 256 bytes would
take 84 us, which is a long time to stall the CPU. Chipsets may not be
designed to post this much data to LPC; therefore, the CPU itself is
stalled for much of this time. Sending 1 kB would take 350 ?s. Therefore,
even if the TPM_STS_x.burstCount field is a high value, software SHOULD
be interruptible during this period."
[3] From the TCG Specification 2.0, "TCG PC Client Platform TPM Profile
(PTP) Specification":
"It takes roughly 330 ns per byte transfer on LPC. 256 bytes would take
84 us. Chipsets may not be designed to post this much data to LPC;
therefore, the CPU itself is stalled for much of this time. Sending 1 kB
would take 350 us. Therefore, even if the TPM_STS_x.burstCount field is a
high value, software should be interruptible during this period. For SPI,
assuming 20MHz clock and 64-byte transfers, it would take about 120 usec
to move 256B of data. Sending 1kB would take about 500 usec. If the
transactions are done using 4 bytes at a time, then it would take about
1 msec. to transfer 1kB of data."
Signed-off-by: Nayna Jain <nayna@linux.vnet.ibm.com>
Reviewed-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Acked-by: Jay Freyensee <why2jjj.linux@gmail.com>
---
drivers/char/tpm/tpm.h | 4 +++-
drivers/char/tpm/tpm_tis_core.c | 5 +++--
2 files changed, 6 insertions(+), 3 deletions(-)
diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
index 7e797377e1eb..f0e4d290c347 100644
--- a/drivers/char/tpm/tpm.h
+++ b/drivers/char/tpm/tpm.h
@@ -54,7 +54,9 @@ enum tpm_timeout {
TPM_TIMEOUT = 5, /* msecs */
TPM_TIMEOUT_RETRY = 100, /* msecs */
TPM_TIMEOUT_RANGE_US = 300, /* usecs */
- TPM_TIMEOUT_POLL = 1 /* msecs */
+ TPM_TIMEOUT_POLL = 1, /* msecs */
+ TPM_TIMEOUT_USECS_MIN = 100, /* usecs */
+ TPM_TIMEOUT_USECS_MAX = 500 /* usecs */
};
/* TPM addresses */
diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
index 021e6b68f2db..bbd8eed30e57 100644
--- a/drivers/char/tpm/tpm_tis_core.c
+++ b/drivers/char/tpm/tpm_tis_core.c
@@ -84,7 +84,8 @@ static int wait_for_tpm_stat(struct tpm_chip *chip, u8 mask,
}
} else {
do {
- tpm_msleep(TPM_TIMEOUT_POLL);
+ usleep_range(TPM_TIMEOUT_USECS_MIN,
+ TPM_TIMEOUT_USECS_MAX);
status = chip->ops->status(chip);
if ((status & mask) == mask)
return 0;
@@ -226,7 +227,7 @@ static int get_burstcount(struct tpm_chip *chip)
burstcnt = (value >> 8) & 0xFFFF;
if (burstcnt)
return burstcnt;
- tpm_msleep(TPM_TIMEOUT_POLL);
+ usleep_range(TPM_TIMEOUT_USECS_MIN, TPM_TIMEOUT_USECS_MAX);
} while (time_before(jiffies, stop));
return -EBUSY;
}
--
2.13.3
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