linux-kernel - [PATCH] jz4740-battery: Correct voltage change check

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Message-Id: <1456675548-16692-1-git-send-email-maarten@treewalker.org>
Date:	Sun, 28 Feb 2016 17:05:48 +0100
From:	Maarten ter Huurne <maarten@...ewalker.org>
To:	Lars-Peter Clausen <lars@...afoo.de>
Cc:	Sebastian Reichel <sre@...nel.org>,
	Dmitry Eremin-Solenikov <dbaryshkov@...il.com>,
	David Woodhouse <dwmw2@...radead.org>,
	linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
	Maarten ter Huurne <maarten@...ewalker.org>
Subject: [PATCH] jz4740-battery: Correct voltage change check

The check is supposed to avoid redundant update notifications, so it
should check for the difference between old and new voltage exceeding
a threshold.

Also make sure the result of a failed read is never stored.

Signed-off-by: Maarten ter Huurne <maarten@...ewalker.org>
---
 drivers/power/jz4740-battery.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/power/jz4740-battery.c b/drivers/power/jz4740-battery.c
index abdfc21..88f04f4 100644
--- a/drivers/power/jz4740-battery.c
+++ b/drivers/power/jz4740-battery.c
@@ -208,7 +208,7 @@ static void jz_battery_update(struct jz_battery *jz_battery)
 	}
 
 	voltage = jz_battery_read_voltage(jz_battery);
-	if (abs(voltage - jz_battery->voltage) < 50000) {
+	if (voltage >= 0 && abs(voltage - jz_battery->voltage) > 50000) {
 		jz_battery->voltage = voltage;
 		has_changed = true;
 	}
-- 
2.6.2