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From:   Sasha Levin <sashal@kernel.org>
To:     linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc:     Gwendal Grignou <gwendal@chromium.org>,
        Enric Balletbo i Serra <enric.balletbo@collabora.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH AUTOSEL 5.8 20/62] platform/chrome: cros_ec_sensorhub: Fix EC timestamp overflow
Date:   Fri, 21 Aug 2020 12:13:41 -0400
Message-Id: <20200821161423.347071-20-sashal@kernel.org>
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From: Gwendal Grignou <gwendal@chromium.org>

[ Upstream commit e48bc01ed5adec203676c735365373b31c3c7600 ]

EC is using 32 bit timestamps (us), and before converting it to 64bit
they were not casted, so it would overflow every 4s.
Regular overflow every ~70 minutes was not taken into account either.

Signed-off-by: Gwendal Grignou <gwendal@chromium.org>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/platform/chrome/cros_ec_sensorhub_ring.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/platform/chrome/cros_ec_sensorhub_ring.c b/drivers/platform/chrome/cros_ec_sensorhub_ring.c
index 24e48d96ed766..b1c641c72f515 100644
--- a/drivers/platform/chrome/cros_ec_sensorhub_ring.c
+++ b/drivers/platform/chrome/cros_ec_sensorhub_ring.c
@@ -419,9 +419,7 @@ cros_ec_sensor_ring_process_event(struct cros_ec_sensorhub *sensorhub,
 			 * Disable filtering since we might add more jitter
 			 * if b is in a random point in time.
 			 */
-			new_timestamp = fifo_timestamp -
-					fifo_info->timestamp  * 1000 +
-					in->timestamp * 1000;
+			new_timestamp = c - b * 1000 + a * 1000;
 			/*
 			 * The timestamp can be stale if we had to use the fifo
 			 * info timestamp.
-- 
2.25.1