[PATCH v2] tpm_tis_spi_main: set cs_change = 0 when timesout

[wanghongzhe]

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

v1 -> v2:
 - fix spi_xfer.cs_change to spi_xfer->cs_change

Signed-off-by: wanghongzhe <wanghongzhe@xxxxxxxxxx>
---
 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