linux-kernel - [PATCH 2/2] regulator: as3711: Fix the logic in as3711_sel

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <1353689602.3260.7.camel@phoenix>
Date:	Sat, 24 Nov 2012 00:53:22 +0800
From:	Axel Lin <axel.lin@...ics.com>
To:	Mark Brown <broonie@...nsource.wolfsonmicro.com>
Cc:	Guennadi Liakhovetski <g.liakhovetski@....de>,
	Liam Girdwood <lrg@...com>, linux-kernel@...r.kernel.org
Subject: [PATCH 2/2] regulator: as3711: Fix the logic in as3711_sel_check

Below equation means the "voltage" is the "smallest" voltage within specific
range.

ret = DIV_ROUND_UP(min - bottom) / step;
voltage = ret * step + bottom;

If we do try 1 down when (voltage > max), new voltage is then less than min
voltage. Which means the new voltage is not in the requested voltage range.

This patch also includes below cleanups:
- Use DIV_ROUND_UP
- rename variable 'ret' to 'sel' for better readability because as3711_sel_check
  returns the selector.

Signed-off-by: Axel Lin <axel.lin@...ics.com>
---
 drivers/regulator/as3711-regulator.c |   23 ++++++++---------------
 1 file changed, 8 insertions(+), 15 deletions(-)

diff --git a/drivers/regulator/as3711-regulator.c b/drivers/regulator/as3711-regulator.c
index 5e813b9..2f1341d 100644
--- a/drivers/regulator/as3711-regulator.c
+++ b/drivers/regulator/as3711-regulator.c
@@ -93,24 +93,17 @@ static int as3711_bound_check(struct regulator_dev *rdev,
 
 static int as3711_sel_check(int min, int max, int bottom, int step)
 {
-	int ret, voltage;
+	int sel, voltage;
 
 	/* Round up min, when dividing: keeps us within the range */
-	ret = (min - bottom + step - 1) / step;
-	voltage = ret * step + bottom;
+	sel = DIV_ROUND_UP(min - bottom, step);
+	voltage = sel * step + bottom;
 	pr_debug("%s(): select %d..%d in %d+N*%d: %d\n", __func__,
-	       min, max, bottom, step, ret);
-	if (voltage > max) {
-		/*
-		 * Try 1 down. It will take us below min, but as long we stay
-		 * above bottom, we're fine.
-		 */
-		ret--;
-		voltage = ret * step + bottom;
-		if (voltage < bottom)
-			return -EINVAL;
-	}
-	return ret;
+	       min, max, bottom, step, sel);
+	if (voltage > max)
+		return -EINVAL;
+
+	return sel;
 }
 
 static int as3711_map_voltage_sd(struct regulator_dev *rdev,
-- 
1.7.9.5



--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/