On Tue, Oct 17, 2017 at 04:32:31PM -0400, Nayna Jain wrote:
> The existing wait_for_tpm_stat() polls for the chip status after
> 5msec sleep. As per TCG ddwg input, it is expected that tpm might
> return status in few usec. So, reducing the delay in polling to
> 1msec.
> Similarly, get_burstcount() function sleeps for 5msec before
> retrying for next query to burstcount in a loop. If it takes
> lesser time for TPM to return, this 5msec delay is longer than
> necessary.
>
> After this change, performance on a TPM 1.2 with an 8 byte
> burstcount for 1000 extends improved from ~14sec to ~9sec.
>
> Signed-off-by: Nayna Jain <na...@linux.vnet.ibm.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakki...@linux.intel.com>
/Jarkko
> ---
> drivers/char/tpm/tpm_tis_core.c | 10 ++++++++--
> 1 file changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
> index 993328ae988c..8b55fdaa67f2 100644
> --- a/drivers/char/tpm/tpm_tis_core.c
> +++ b/drivers/char/tpm/tpm_tis_core.c
> @@ -31,6 +31,12 @@
> #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 bool wait_for_tpm_stat_cond(struct tpm_chip *chip, u8 mask,
> bool check_cancel, bool *canceled)
> {
> @@ -82,7 +88,7 @@ static int wait_for_tpm_stat(struct tpm_chip *chip, u8 mask,
> }
> } else {
> do {
> - tpm_msleep(TPM_TIMEOUT);
> + tpm_msleep(TPM_POLL_SLEEP);
> status = chip->ops->status(chip);
> if ((status & mask) == mask)
> return 0;
> @@ -224,7 +230,7 @@ static int get_burstcount(struct tpm_chip *chip)
> burstcnt = (value >> 8) & 0xFFFF;
> if (burstcnt)
> return burstcnt;
> - tpm_msleep(TPM_TIMEOUT);
> + tpm_msleep(TPM_POLL_SLEEP);
> } while (time_before(jiffies, stop));
> return -EBUSY;
> }
> --
> 2.13.3
>
