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From: Daniel Mack <daniel@caiaq.de>
To: linux-kernel@vger.kernel.org
Cc: Daniel Mack <daniel@caiaq.de>,
	Szabolcs Gyurko <szabolcs.gyurko@tlt.hu>,
	Matt Reimer <mreimer@vpop.net>, Anton Vorontsov <cbou@mail.ru>
Subject: [PATCH] ds2760: fix integer overflow for time_to_empty_now
Date: Fri, 24 Jul 2009 15:19:33 +0200	[thread overview]
Message-ID: <1248441573-32712-1-git-send-email-daniel@caiaq.de> (raw)

On the device we're currently developing, battery sizes of ~2.8Ah and
current flow of ~600mA are typical.

With that values, the life_sec computation overflows due to the
multiplication by 3600.

Signed-off-by: Daniel Mack <daniel@caiaq.de>
Cc: Szabolcs Gyurko <szabolcs.gyurko@tlt.hu>
Cc: Matt Reimer <mreimer@vpop.net>
Cc: Anton Vorontsov <cbou@mail.ru>

Signed-off-by: Daniel Mack <daniel@caiaq.de>
---
 drivers/power/ds2760_battery.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/power/ds2760_battery.c b/drivers/power/ds2760_battery.c
index d545fee..5d30dc0 100644
--- a/drivers/power/ds2760_battery.c
+++ b/drivers/power/ds2760_battery.c
@@ -212,8 +212,8 @@ static int ds2760_battery_read_status(struct ds2760_device_info *di)
 		di->rem_capacity = 100;
 
 	if (di->current_uA)
-		di->life_sec = -((di->accum_current_uAh - di->empty_uAh) *
-				 3600L) / di->current_uA;
+		di->life_sec = -((di->accum_current_uAh - di->empty_uAh) * 36L)
+					/ (di->current_uA / 100L);
 	else
 		di->life_sec = 0;
 
-- 
1.6.3.1


             reply	other threads:[~2009-07-24 13:19 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-07-24 13:19 Daniel Mack [this message]
2009-07-30 14:00 ` Anton Vorontsov
2009-07-30 14:12   ` Daniel Mack
2009-07-30 14:26     ` Anton Vorontsov
2009-07-30 17:40       ` Daniel Mack

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