From 0387ee1b95d1cf21156dc73ccb7a34a8884b0958 Mon Sep 17 00:00:00 2001 From: Luuk Paulussen 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 Link: https://lore.kernel.org/r/20191205231659.1301-1-luuk.paulussen@alliedtelesis.co.nz cc: stable@vger.kernel.org Signed-off-by: Guenter Roeck Signed-off-by: Greg Kroah-Hartman --- drivers/hwmon/adt7475.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/hwmon/adt7475.c b/drivers/hwmon/adt7475.c index 6c64d50c9aae..01c2eeb02aa9 100644 --- a/drivers/hwmon/adt7475.c +++ b/drivers/hwmon/adt7475.c @@ -294,9 +294,10 @@ 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); }