On Tue, 2018-04-17 at 09:12 -0400, Nayna Jain wrote:
> The TPM polling code in tpm_transmit sleeps in each loop iteration for
> 5 msecs. However, the TPM might return earlier, and thus waiting for
> 5 msecs adds an unnecessary delay. This patch reduces the polling sleep
> time in tpm_transmit() from 5 msecs to 1 msecs.
>
> Additionally, this patch renames TPM_POLL_SLEEP and moves it to tpm.h as
> an enum value.
>
> After this change, performance on a TPM 1.2 with an 8 byte burstcount
> for 1000 extends improved from ~14 sec to ~10.7 sec.
>
> Signed-off-by: Nayna Jain <nayna@xxxxxxxxxxxxxxxxxx>
Reviewed-by: Mimi Zohar <zohar@xxxxxxxxxxxxxxxxxx>
> ---
> drivers/char/tpm/tpm-interface.c | 2 +-
> drivers/char/tpm/tpm.h | 3 ++-
> drivers/char/tpm/tpm_tis_core.c | 10 ++--------
> 3 files changed, 5 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
> index 9e80a953d693..a676d8ad5992 100644
> --- a/drivers/char/tpm/tpm-interface.c
> +++ b/drivers/char/tpm/tpm-interface.c
> @@ -470,7 +470,7 @@ ssize_t tpm_transmit(struct tpm_chip *chip, struct tpm_space *space,
> goto out;
> }
>
> - tpm_msleep(TPM_TIMEOUT);
> + tpm_msleep(TPM_TIMEOUT_POLL);
> rmb();
> } while (time_before(jiffies, stop));
>
> diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
> index f895fba4e20d..7e797377e1eb 100644
> --- a/drivers/char/tpm/tpm.h
> +++ b/drivers/char/tpm/tpm.h
> @@ -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 */
> diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
> index da074e3db19b..021e6b68f2db 100644
> --- a/drivers/char/tpm/tpm_tis_core.c
> +++ b/drivers/char/tpm/tpm_tis_core.c
> @@ -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 @@ static int wait_for_tpm_stat(struct tpm_chip *chip, u8 mask,
> }
> } else {
> do {
> - tpm_msleep(TPM_POLL_SLEEP);
> + tpm_msleep(TPM_TIMEOUT_POLL);
> status = chip->ops->status(chip);
> if ((status & mask) == mask)
> return 0;
> @@ -232,7 +226,7 @@ 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;
> }
