tpm: reduce poll sleep time in tpm_transmit() (59f5a6b0) · Commits · 戴 / test

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>

drivers/char/tpm/tpm-interface.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -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));

drivers/char/tpm/tpm.h

+2 −1

Original line number	Diff line number	Diff line
		@@ -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 */

drivers/char/tpm/tpm_tis_core.c

+2 −8

Original line number	Diff line number	Diff line
		@@ -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;
		}

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