On Wed, 9 Nov 2011 20:33:27 +0800, Eric Miao wrote: > On Wed, Nov 9, 2011 at 8:22 PM, Jean Delvare <khali@xxxxxxxxxxxx> wrote: > > Hi Eric, > > > > On Wed, 9 Nov 2011 19:15:03 +0800, Eric Miao wrote: > >> This patch fixed the inconsistent max1111 sysfs interface as pointed > >> out by Jean Delvare: > >> > >> It was pointed to me that the max1111 driver doesn't implement the > >> standard sysfs interface for hwmon drivers (as described in > >> Documentation/hwmon/sysfs-interface). It exports files adc[0-3]_in, > >> which > >> aren't part of the standard interface. Presumably these should be > >> renamed to in[0-3]_input. Renaming them is probably not sufficient > >> though, as I see no scaling done in the driver. As the MAX1111 chip has > >> a documented full scale of 2.048V, I take it that the LSB of the ADC > >> has a weight of 8 mV. Exporting raw register values to user-space is > >> not OK. > >> > >> Reported-by: Jean Delvare <khali@xxxxxxxxxxxx> > >> Signed-off-by: Eric Miao <eric.y.miao@xxxxxxxxx> > >> --- > >> drivers/hwmon/max1111.c | 13 +++++++------ > >> 1 files changed, 7 insertions(+), 6 deletions(-) > >> > >> diff --git a/drivers/hwmon/max1111.c b/drivers/hwmon/max1111.c > >> index c97b78e..0e9fcfd 100644 > >> --- a/drivers/hwmon/max1111.c > >> +++ b/drivers/hwmon/max1111.c > >> @@ -106,11 +106,12 @@ static ssize_t show_adc(struct device *dev, > >> if (ret < 0) > >> return ret; > >> > >> - return sprintf(buf, "%d\n", ret); > >> + /* assume the reference voltage to be 2.048V */ > >> + return sprintf(buf, "%d\n", 2048 * 256 / ret); > > > > I bet you did not actually test your changes? ret == 0 would obviously > > crash the driver. The formula looks wrong anyway, should be 2048 * > > ret / 256. Or in short ret * 8, i.e. LSB weight of the ADC is 8 mV. > > > > Oops, shame to death. > > How about simply '2048 * ret / 256' to make it clear and leave it to > the compiler to optimize? I find the concept of LSB weight clear enough, but ultimately that's up to you, as long as the compiler actually optimizes it. -- Jean Delvare _______________________________________________ lm-sensors mailing list lm-sensors@xxxxxxxxxxxxxx http://lists.lm-sensors.org/mailman/listinfo/lm-sensors
