On Sat, 19 Aug 2023, Guenter Roeck wrote:
> On Sat, Aug 19, 2023 at 02:20:32PM +0000, Huibin Shi wrote:
> > Hi Guenter,
> >
> > Thanks for your comments. Probably, I should not resubmit patch too rushed. I will add version number to subject and change log in cover letter for next resubmission.
> >
> > See my comments below. Please let me know whether you accept my explanation.
> >
> > Henry
> > -----Original Message-----
> [ ... ]
>
> > > +
> > > +static u32 temp_get(void)
> > > +{
> > > + u32 reg;
> > > +
> > > + mutex_lock(&mec_io_mutex);
> > > + /* Select memory region */
> > > + outb(IO_REG_BANK, EC_ADDR_MSB);
> > > + outb(0xc, EC_ADDR_LSB);
> > > + /* Get current data from the address */
> > > + reg = inl(MEC_DATA(DEFAULT_CHAN_LO));
> > > + mutex_unlock(&mec_io_mutex);
> > > +
> > > + return (reg >> 16) / 10;
> >
> > The hwmon ABI expects temperatures to be reported in milli-degrees C.
> > The above sets the maximum temperature to 65,535 / 10 = 6,553 milli-degrees or 6.553 degrees C. It is very unlikely that this is correct.
> >
> > Again, I commented on this before.
> >
> > Henry: this is due to an internal implementation of MIcor-controller firmware, instead of putting real temperature to the register, it put (real temperature * 10 ) to the register. So, in order to report correct temperature to user space application, the read value is divided by 10, then report to user space.
> >
> > Please let me know if you accept this. If not, I can change the code, but let user space application to do adjustment.
>
> No, I do not accept this. I do not believe that the maximum temperature
> reported by the microcontroller is 6.553 degrees C. I suspect it reports
> 10th of degrees C. In that case, the number reported should be multiplied
> by 100 to make it milli-degrees C as expected by the ABI.
...And for that multiplication, please use the constant defined in
include/linux/units.h instead of a literal.
And please do version the patches properly, it's getting messy to track
which version is which (if something is new or not). If you use git
format-patch, it has an argument that can be used to add the version, no
need to add it by hand.
--
i.
