blob: 43a5a2556c85269fd78cd70a6089bdd083c27260 [file] [log] [blame]
From 8c5dbbefb7b739adb5e941c44c9441dfa89cb702 Mon Sep 17 00:00:00 2001
From: Luuk Paulussen <luuk.paulussen@alliedtelesis.co.nz>
Date: Fri, 6 Dec 2019 12:16:59 +1300
Subject: [PATCH] hwmon: (adt7475) Make volt2reg return same reg as reg2volt
input
commit cf3ca1877574a306c0207cbf7fdf25419d9229df upstream.
reg2volt returns the voltage that matches a given register value.
Converting this back the other way with volt2reg didn't return the same
register value because it used truncation instead of rounding.
This meant that values read from sysfs could not be written back to sysfs
to set back the same register value.
With this change, volt2reg will return the same value for every voltage
previously returned by reg2volt (for the set of possible input values)
Signed-off-by: Luuk Paulussen <luuk.paulussen@alliedtelesis.co.nz>
Link: https://lore.kernel.org/r/20191205231659.1301-1-luuk.paulussen@alliedtelesis.co.nz
cc: stable@vger.kernel.org
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
diff --git a/drivers/hwmon/adt7475.c b/drivers/hwmon/adt7475.c
index c3c6031a7285..e3831086bac5 100644
--- a/drivers/hwmon/adt7475.c
+++ b/drivers/hwmon/adt7475.c
@@ -293,9 +293,10 @@ static inline u16 volt2reg(int channel, long volt, u8 bypass_attn)
long reg;
if (bypass_attn & (1 << channel))
- reg = (volt * 1024) / 2250;
+ reg = DIV_ROUND_CLOSEST(volt * 1024, 2250);
else
- reg = (volt * r[1] * 1024) / ((r[0] + r[1]) * 2250);
+ reg = DIV_ROUND_CLOSEST(volt * r[1] * 1024,
+ (r[0] + r[1]) * 2250);
return clamp_val(reg, 0, 1023) & (0xff << 2);
}
--
2.7.4