linux-kernel - [PATCH v1] tpm_tis_spi_main: set cs

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Date:   Fri, 5 Feb 2021 14:42:05 +0800
From:   wanghongzhe <wanghongzhe@...wei.com>
To:     <peterhuewe@....de>, <jarkko@...nel.org>, <jgg@...pe.ca>
CC:     <linux-integrity@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: [PATCH v1] tpm_tis_spi_main: set cs_change = 0 when timesout

when i reach TPM_RETRY, the cs cannot  change back to 'high'.
So the TPM chips thinks this communication is not over.
And next times communication cannot be effective because
the communications mixed up with the last time.

Signed-off-by: wanghongzhe <wanghongzhe@...wei.com>
---
 drivers/char/tpm/tpm_tis_spi_main.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/drivers/char/tpm/tpm_tis_spi_main.c b/drivers/char/tpm/tpm_tis_spi_main.c
index 3856f6ebcb34..6c52cbb28881 100644
--- a/drivers/char/tpm/tpm_tis_spi_main.c
+++ b/drivers/char/tpm/tpm_tis_spi_main.c
@@ -64,8 +64,18 @@ static int tpm_tis_spi_flow_control(struct tpm_tis_spi_phy *phy,
 				break;
 		}
 
-		if (i == TPM_RETRY)
+		if (i == TPM_RETRY) {
+			/* change back to 'high',
+			 * So the TPM chips thinks the last communication
+			 * is done.
+			 */
+			spi_xfer.cs_change = 0;
+			spi_xfer->len = 1;
+			spi_message_init(&m);
+			spi_message_add_tail(spi_xfer, &m);
+			ret = spi_sync_locked(phy->spi_device, &m);
 			return -ETIMEDOUT;
+		}
 	}
 
 	return 0;
-- 
2.19.1