linux-kernel - [34-longterm 031/209] olpc_battery: Fix endian neutral breakage for s16 values

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Message-Id: <1302803039-9400-32-git-send-email-paul.gortmaker@windriver.com>
Date:	Thu, 14 Apr 2011 13:41:01 -0400
From:	Paul Gortmaker <paul.gortmaker@...driver.com>
To:	stable@...nel.org, linux-kernel@...r.kernel.org
Cc:	stable-review@...nel.org, "Richard A. Smith" <richard@...top.org>,
	Daniel Drake <dsd@...top.org>,
	Anton Vorontsov <cbouatmailru@...il.com>,
	Paul Gortmaker <paul.gortmaker@...driver.com>
Subject: [34-longterm 031/209] olpc_battery: Fix endian neutral breakage for s16 values

From: Richard A. Smith <richard@...top.org>

  =====================================================================
  | This is a commit scheduled for the next v2.6.34 longterm release. |
  | If you see a problem with using this for longterm, please comment.|
  =====================================================================

commit 7cfbb29466633e6ecdc14f76a693c8478c2b22af upstream.

When the driver was updated to be endian neutral (8e9c7716c)
the signed part of the s16 values was lost.  This is because be16_to_cpu()
returns an unsigned value.  This patch casts the values back to a s16
number prior to the the implicit cast up to an int.

Signed-off-by: Richard A. Smith <richard@...top.org>
Signed-off-by: Daniel Drake <dsd@...top.org>
Signed-off-by: Anton Vorontsov <cbouatmailru@...il.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@...driver.com>
---
 drivers/power/olpc_battery.c |    8 ++++----
 1 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/power/olpc_battery.c b/drivers/power/olpc_battery.c
index 8fefe5a..4b38eaa 100644
--- a/drivers/power/olpc_battery.c
+++ b/drivers/power/olpc_battery.c
@@ -271,14 +271,14 @@ static int olpc_bat_get_property(struct power_supply *psy,
 		if (ret)
 			return ret;
 
-		val->intval = (int)be16_to_cpu(ec_word) * 9760L / 32;
+		val->intval = (s16)be16_to_cpu(ec_word) * 9760L / 32;
 		break;
 	case POWER_SUPPLY_PROP_CURRENT_AVG:
 		ret = olpc_ec_cmd(EC_BAT_CURRENT, NULL, 0, (void *)&ec_word, 2);
 		if (ret)
 			return ret;
 
-		val->intval = (int)be16_to_cpu(ec_word) * 15625L / 120;
+		val->intval = (s16)be16_to_cpu(ec_word) * 15625L / 120;
 		break;
 	case POWER_SUPPLY_PROP_CAPACITY:
 		ret = olpc_ec_cmd(EC_BAT_SOC, NULL, 0, &ec_byte, 1);
@@ -299,7 +299,7 @@ static int olpc_bat_get_property(struct power_supply *psy,
 		if (ret)
 			return ret;
 
-		val->intval = (int)be16_to_cpu(ec_word) * 100 / 256;
+		val->intval = (s16)be16_to_cpu(ec_word) * 100 / 256;
 		break;
 	case POWER_SUPPLY_PROP_TEMP_AMBIENT:
 		ret = olpc_ec_cmd(EC_AMB_TEMP, NULL, 0, (void *)&ec_word, 2);
@@ -313,7 +313,7 @@ static int olpc_bat_get_property(struct power_supply *psy,
 		if (ret)
 			return ret;
 
-		val->intval = (int)be16_to_cpu(ec_word) * 6250 / 15;
+		val->intval = (s16)be16_to_cpu(ec_word) * 6250 / 15;
 		break;
 	case POWER_SUPPLY_PROP_SERIAL_NUMBER:
 		ret = olpc_ec_cmd(EC_BAT_SERIAL, NULL, 0, (void *)&ser_buf, 8);
-- 
1.7.4.4

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