From 451738188482a34603a184e868893f407998bdd4 Mon Sep 17 00:00:00 2001 From: Nayna Jain Date: Fri, 10 Nov 2017 17:16:35 -0500 Subject: [PATCH 08/10] tpm: ignore burstcount to improve tpm_tis send() performance MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The TPM burstcount status indicates the number of bytes that can be sent to the TPM without causing bus wait states.  Effectively, it is the number of empty bytes in the command FIFO. This patch optimizes the tpm_tis_send_data() function by checking the burstcount only once. And if the burstcount is valid, it writes all the bytes at once, permitting wait state. After this change, performance on a TPM 1.2 with an 8 byte burstcount for 1000 extends improved from ~41sec to ~14sec. Suggested-by: Ken Goldman in conjunction with the TPM Device Driver work group. Signed-off-by: Nayna Jain Acked-by: Mimi Zohar Reviewed-by: Jarkko Sakkinen Tested-by: Jarkko Sakkinen Signed-off-by: Jarkko Sakkinen Signed-off-by: Dongqi Chen Signed-off-by: Jiping Ma --- drivers/char/tpm/tpm_tis_core.c | 43 ++++++++++++--------------------- 1 file changed, 15 insertions(+), 28 deletions(-) diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c index a2e0395cbe61..2c69fde1e4e5 100644 --- a/drivers/char/tpm/tpm_tis_core.c +++ b/drivers/char/tpm/tpm_tis_core.c @@ -330,7 +330,6 @@ static int tpm_tis_send_data(struct tpm_chip *chip, const u8 *buf, size_t len) { struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev); int rc, status, burstcnt; - size_t count = 0; bool itpm = priv->flags & TPM_TIS_ITPM_WORKAROUND; status = tpm_tis_status(chip); @@ -343,36 +342,24 @@ static int tpm_tis_send_data(struct tpm_chip *chip, const u8 *buf, size_t len) goto out_err; } } - - while (count < len - 1) { - burstcnt = get_burstcount(chip); - if (burstcnt < 0) { - dev_err(&chip->dev, "Unable to read burstcount\n"); - rc = burstcnt; - goto out_err; - } - burstcnt = min_t(int, burstcnt, len - count - 1); - rc = tpm_tis_write_bytes(priv, TPM_DATA_FIFO(priv->locality), - burstcnt, buf + count); - if (rc < 0) - goto out_err; - - count += burstcnt; - - if (wait_for_tpm_stat(chip, TPM_STS_VALID, chip->timeout_c, - &priv->int_queue, false) < 0) { - rc = -ETIME; - goto out_err; - } - status = tpm_tis_status(chip); - if (!itpm && (status & TPM_STS_DATA_EXPECT) == 0) { - rc = -EIO; - goto out_err; - } + /* + * Get the initial burstcount to ensure TPM is ready to + * accept data, even when waiting for burstcount is disabled. + */ + burstcnt = get_burstcount(chip); + if (burstcnt < 0) { + dev_err(&chip->dev, "Unable to read burstcount\n"); + rc = burstcnt; + goto out_err; } + rc = tpm_tis_write_bytes(priv, TPM_DATA_FIFO(priv->locality), + len -1, buf); + if (rc < 0) + goto out_err; + /* write last byte */ - rc = tpm_tis_write8(priv, TPM_DATA_FIFO(priv->locality), buf[count]); + rc = tpm_tis_write8(priv, TPM_DATA_FIFO(priv->locality), buf[len-1]); if (rc < 0) goto out_err; -- 2.29.2