From 87434f58be31a96d72b5ddbb98d53307300e0024 Mon Sep 17 00:00:00 2001 From: Alexander Steffen Date: Thu, 31 Aug 2017 19:18:57 +0200 Subject: [PATCH] tpm: Use dynamic delay to wait for TPM 2.0 self test result In order to avoid delaying the code longer than necessary while still giving the TPM enough time to execute the self tests asynchronously, start with a small delay between two polls and increase it each round. Signed-off-by: Alexander Steffen Reviewed-by: Jarkko Sakkinen Tested-by: Jarkko Sakkinen Signed-off-by: Jarkko Sakkinen --- drivers/char/tpm/tpm2-cmd.c | 17 +++++++++-------- 1 file changed, 9 insertions(+), 8 deletions(-) diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c index 8e940a5..2178437 100644 --- a/drivers/char/tpm/tpm2-cmd.c +++ b/drivers/char/tpm/tpm2-cmd.c @@ -877,20 +877,17 @@ static int tpm2_start_selftest(struct tpm_chip *chip, bool full) static int tpm2_do_selftest(struct tpm_chip *chip) { int rc; - unsigned int loops; - unsigned int delay_msec = 100; - unsigned long duration; - int i; - - duration = tpm2_calc_ordinal_duration(chip, TPM2_CC_SELF_TEST); + unsigned int delay_msec = 20; + long duration; - loops = jiffies_to_msecs(duration) / delay_msec; + duration = jiffies_to_msecs( + tpm2_calc_ordinal_duration(chip, TPM2_CC_SELF_TEST)); rc = tpm2_start_selftest(chip, false); if (rc) return rc; - for (i = 0; i < loops; i++) { + while (duration > 0) { /* Attempt to read a PCR value */ rc = tpm2_pcr_read(chip, 0, NULL); if (rc < 0) @@ -900,6 +897,10 @@ static int tpm2_do_selftest(struct tpm_chip *chip) break; tpm_msleep(delay_msec); + duration -= delay_msec; + + /* wait longer the next round */ + delay_msec *= 2; } return rc; -- 2.7.4