From 10460bc1cfdea19dbab2289a63b4be0c874d29f2 Mon Sep 17 00:00:00 2001
From: Christophe RICARD <christophe.ricard@gmail.com>
Date: Sat, 13 Feb 2016 16:15:30 +0100
Subject: [PATCH] tpm/st33zp24/spi: Improve st33zp24_spi_evaluate_latency

Add check in st33zp24_spi_evaluate_latency helping to diagnose if the chip
is present or in a bad state.

Signed-off-by: Christophe Ricard <christophe-h.ricard@st.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
---
 drivers/char/tpm/st33zp24/spi.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/char/tpm/st33zp24/spi.c b/drivers/char/tpm/st33zp24/spi.c
index 08e6bf54d7dd..a2ef8ec4ba80 100644
--- a/drivers/char/tpm/st33zp24/spi.c
+++ b/drivers/char/tpm/st33zp24/spi.c
@@ -214,6 +214,11 @@ static int st33zp24_spi_evaluate_latency(void *phy_id)
 						&data, 1);
 		latency++;
 	}
+	if (status < 0)
+		return status;
+	if (latency == MAX_SPI_LATENCY)
+		return -ENODEV;
+
 	return latency - 1;
 } /* evaluate_latency() */
 
-- 
2.20.1