From e82060f0cf390ba8e4f79a54e68cef9a38088104 Mon Sep 17 00:00:00 2001 From: Nayna Jain Date: Fri, 10 Nov 2017 17:16:35 -0500 Subject: [PATCH] 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 --- tpm_tis_core.c | 42 +++++++++++++++--------------------------- 1 file changed, 15 insertions(+), 27 deletions(-) diff --git a/tpm_tis_core.c b/tpm_tis_core.c index a338701..a6b4149 100644 --- a/tpm_tis_core.c +++ b/tpm_tis_core.c @@ -256,7 +256,6 @@ static int tpm_tis_send_data(struct tpm_chip *chip, 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); @@ -270,36 +269,25 @@ static int tpm_tis_send_data(struct tpm_chip *chip, u8 *buf, size_t len) } } - 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, 1, - &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; -- 1.8.3.1