On Mon, Nov 27, 2017 at 01:39:14PM -0800, Robert Lippert wrote: > Power values in the 100s of watt range can easily blow past > 32bit math limits when processing everything in microwatts. > > Use 64bit math instead to avoid these issues on common 32bit ARM > BMC platforms. > > Signed-off-by: Robert Lippert <rlippert@xxxxxxxxxx> > --- > drivers/hwmon/pmbus/pmbus_core.c | 23 ++++++++++++++--------- > 1 file changed, 14 insertions(+), 9 deletions(-) > > diff --git a/drivers/hwmon/pmbus/pmbus_core.c b/drivers/hwmon/pmbus/pmbus_core.c > index 52a58b8b6e1b..ff701502974a 100644 > --- a/drivers/hwmon/pmbus/pmbus_core.c > +++ b/drivers/hwmon/pmbus/pmbus_core.c > @@ -21,6 +21,7 @@ > > #include <linux/debugfs.h> > #include <linux/kernel.h> > +#include <linux/math64.h> > #include <linux/module.h> > #include <linux/init.h> > #include <linux/err.h> > @@ -499,8 +500,9 @@ static long pmbus_reg2data_linear(struct pmbus_data *data, > static long pmbus_reg2data_direct(struct pmbus_data *data, > struct pmbus_sensor *sensor) > { > - long val = (s16) sensor->data; > - long m, b, R; > + s64 val = (s16) sensor->data; > + s64 b, R; Do b and R have to be s64 ? Seems excessive. > + s32 m; > > m = data->info->m[sensor->class]; > b = data->info->b[sensor->class]; > @@ -528,11 +530,12 @@ static long pmbus_reg2data_direct(struct pmbus_data *data, > R--; > } > while (R < 0) { > - val = DIV_ROUND_CLOSEST(val, 10); > + val = div_s64(val + 5LL, 10L); // round closest > R++; > } > > - return (val - b) / m; > + val = div_s64(val - b, m); > + return clamp_val(val, LONG_MIN, LONG_MAX); > } > > /* > @@ -656,7 +659,9 @@ static u16 pmbus_data2reg_linear(struct pmbus_data *data, > static u16 pmbus_data2reg_direct(struct pmbus_data *data, > struct pmbus_sensor *sensor, long val) > { > - long m, b, R; > + s64 b, R; Same question as above - do those have to be s64 ? > + s32 m; > + s64 val64 = val; > > m = data->info->m[sensor->class]; > b = data->info->b[sensor->class]; > @@ -673,18 +678,18 @@ static u16 pmbus_data2reg_direct(struct pmbus_data *data, > R -= 3; /* Adjust R and b for data in milli-units */ > b *= 1000; > } > - val = val * m + b; > + val64 = val64 * m + b; > > while (R > 0) { > - val *= 10; > + val64 *= 10; > R--; > } > while (R < 0) { > - val = DIV_ROUND_CLOSEST(val, 10); > + val64 = div_s64(val64 + 5LL, 10L); // round closest > R++; > } > > - return val; > + return (u16) clamp_val(val64, S16_MIN, S16_MAX); > } > > static u16 pmbus_data2reg_vid(struct pmbus_data *data, > -- > 2.15.0.417.g466bffb3ac-goog > > -- > To unsubscribe from this list: send the line "unsubscribe linux-hwmon" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-hwmon" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html