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 <Alexander.Steffen@infineon.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>

diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
index 8e940a530df8777854f392e1ec21afc93b2aa0fb..2178437e541a96082b407e1f0872cd4bc9c84cbc 100644 (file)
--- 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;