linux-kernel - [PATCH v3 4/4] tpm_tis: Resend command to recover from data transfer errors

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Message-ID: <20230613180259.3525-5-Alexander.Steffen@infineon.com>
Date:   Tue, 13 Jun 2023 20:02:59 +0200
From:   Alexander Steffen <Alexander.Steffen@...ineon.com>
To:     <jarkko@...nel.org>, <linux-integrity@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
CC:     Alexander Steffen <Alexander.Steffen@...ineon.com>
Subject: [PATCH v3 4/4] tpm_tis: Resend command to recover from data transfer errors

Similar to the transmission of TPM responses, also the transmission of TPM
commands may become corrupted. Instead of aborting when detecting such
issues, try resending the command again.

Signed-off-by: Alexander Steffen <Alexander.Steffen@...ineon.com>
---
 drivers/char/tpm/tpm_tis_core.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
index a6d1396413a7..7b13ad4bd6dd 100644
--- a/drivers/char/tpm/tpm_tis_core.c
+++ b/drivers/char/tpm/tpm_tis_core.c
@@ -532,10 +532,17 @@ static int tpm_tis_send_main(struct tpm_chip *chip, const u8 *buf, size_t len)
 	int rc;
 	u32 ordinal;
 	unsigned long dur;
+	unsigned int try;
 
-	rc = tpm_tis_send_data(chip, buf, len);
-	if (rc < 0)
-		return rc;
+	for (try = 0; try < TPM_RETRY; try++) {
+		rc = tpm_tis_send_data(chip, buf, len);
+		if (rc >= 0)
+			/* Data transfer done successfully */
+			break;
+		else if (rc != -EIO)
+			/* Data transfer failed, not recoverable */
+			return rc;
+	}
 
 	/* go and do it */
 	rc = tpm_tis_write8(priv, TPM_STS(priv->locality), TPM_STS_GO);
-- 
2.25.1