linux-kernel - [PATCH] platform: chrome: Fix EC timestamp overflow

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Date:   Tue, 30 Jun 2020 00:52:03 -0700
From:   Gwendal Grignou <gwendal@...omium.org>
To:     bleung@...omium.org, enric.balletbo@...labora.com,
        bhanumaiya@...omium.org
Cc:     groeck@...omium.org, linux-kernel@...r.kernel.org,
        Gwendal Grignou <gwendal@...omium.org>
Subject: [PATCH] platform: chrome: Fix EC timestamp overflow

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 acoun either.

Signed-off-by: Gwendal Grignou <gwendal@...omium.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 23960f3acc0b1..641d91088cee2 100644
--- a/drivers/platform/chrome/cros_ec_sensorhub_ring.c
+++ b/drivers/platform/chrome/cros_ec_sensorhub_ring.c
@@ -465,9 +465,7 @@ 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.
-- 
2.27.0.212.ge8ba1cc988-goog