linux-kernel - [PATCH] [62/223] olpc_battery: Fix endian neutral breakage for s16 values

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Message-Id: <20101212234600.42BE4B27BF@basil.firstfloor.org>
Date:	Mon, 13 Dec 2010 00:46:00 +0100 (CET)
From:	Andi Kleen <andi@...stfloor.org>
To:	richard@...top.org, dsd@...top.org, cbouatmailru@...il.com,
	gregkh@...e.de, ak@...ux.intel.com, linux-kernel@...r.kernel.org,
	stable@...nel.org
Subject: [PATCH] [62/223] olpc_battery: Fix endian neutral breakage for s16 values

2.6.35-longterm review patch.  If anyone has any objections, please let me know.

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

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: Greg Kroah-Hartman <gregkh@...e.de>
Signed-off-by: Andi Kleen <ak@...ux.intel.com>

---
 drivers/power/olpc_battery.c |    8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

Index: linux/drivers/power/olpc_battery.c
===================================================================
--- linux.orig/drivers/power/olpc_battery.c
+++ linux/drivers/power/olpc_battery.c
@@ -271,14 +271,14 @@ static int olpc_bat_get_property(struct
 		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
 		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
 		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);
--
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