tpm: reduce poll sleep time in tpm_transmit()
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>
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@ -489,7 +489,7 @@ static ssize_t tpm_try_transmit(struct tpm_chip *chip,
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goto out;
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}
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tpm_msleep(TPM_TIMEOUT);
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tpm_msleep(TPM_TIMEOUT_POLL);
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rmb();
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} while (time_before(jiffies, stop));
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@ -53,7 +53,8 @@ enum tpm_const {
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enum tpm_timeout {
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TPM_TIMEOUT = 5, /* msecs */
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TPM_TIMEOUT_RETRY = 100, /* msecs */
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TPM_TIMEOUT_RANGE_US = 300 /* usecs */
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TPM_TIMEOUT_RANGE_US = 300, /* usecs */
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TPM_TIMEOUT_POLL = 1 /* msecs */
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};
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/* TPM addresses */
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@ -31,12 +31,6 @@
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#include "tpm.h"
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#include "tpm_tis_core.h"
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/* This is a polling delay to check for status and burstcount.
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* As per ddwg input, expectation is that status check and burstcount
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* check should return within few usecs.
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*/
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#define TPM_POLL_SLEEP 1 /* msec */
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static void tpm_tis_clkrun_enable(struct tpm_chip *chip, bool value);
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static bool wait_for_tpm_stat_cond(struct tpm_chip *chip, u8 mask,
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@ -90,7 +84,7 @@ again:
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}
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} else {
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do {
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tpm_msleep(TPM_POLL_SLEEP);
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tpm_msleep(TPM_TIMEOUT_POLL);
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status = chip->ops->status(chip);
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if ((status & mask) == mask)
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return 0;
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@ -279,7 +273,7 @@ static int get_burstcount(struct tpm_chip *chip)
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burstcnt = (value >> 8) & 0xFFFF;
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if (burstcnt)
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return burstcnt;
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tpm_msleep(TPM_POLL_SLEEP);
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tpm_msleep(TPM_TIMEOUT_POLL);
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} while (time_before(jiffies, stop));
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return -EBUSY;
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}
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