On Thu, 2024-11-14 at 12:00 +0100, Matteo Martelli wrote: > EXTERNAL EMAIL: Do not click links or open attachments unless you > know the content is safe > Hi Matteo, > On Thu, 14 Nov 2024 10:47:02 +0200, <victor.duicu@xxxxxxxxxxxxx> > wrote: > > From: Victor Duicu <victor.duicu@xxxxxxxxxxxxx> > > > > This patch implements ACPI support to Microchip pac1921. > > The driver can read the shunt resistor value and label from the > > ACPI table. > > > > Reviewed-by: Andy Shevchenko <andy.shevchenko@xxxxxxxxx> > > Signed-off-by: Victor Duicu <victor.duicu@xxxxxxxxxxxxx> > > --- > > .... > > > > > > +#define PAC1921_ACPI_GET_uOHMS_VALS 0 > > +#define PAC1921_ACPI_GET_LABEL 1 > > +/* > > + * The maximum acceptable shunt value is 2146.999999 OHM. > > + * This value, which is below INT_MAX, was chosen in order to > > + * allow the readings from dt and ACPI to share the same range > > + * and to simplify the checks. > > + * With this value the maximum current that can be read is > > + * 0.1V / 2146.999999OHM = 46.576 uA > > + * If we use INT_MAX the maximum current that can be read is > > + * 0.1V / 2147.483647OHM = 46.566 uA > > + * The relative error between the two values is > > + * |(46.566 - 46.576) / 46.566| * 100 = 0.0214 > > + */ > > +#define PAC1921_MAX_SHUNT_VALUE_uOHMS 2146999999UL > > + > > Just a minor point about this: if I understand correctly that value > comes from (INT_MAX / MICRO - 1) * MICRO + MAX_MICRO. This was to > simplify the check in a single statement in > pac1921_write_shunt_resistor() > which is called when the shunt resistor is set from *sysfs* (neither > from DT nor ACPI). I'm fine with this value and the new check but I > find > the explanation comment a bit confusing. If you could come up with a > bit > more clear explanation about the reason of such value I think it > would be > better otherwise I am fine with it as it is. Also, maybe use the full > room > for 80 characters per line and UOHMS instead of uOHMS to avoid mixed > case if > you are going with a new version. We could completely remove the need to use a constant below INT_MAX with this check in pac1921_write_shunt_resistor: if ((!val && !val_fract) || ((val >= INT_MAX / MICRO) && (val_fract > INT_MAX % MICRO))) return -EINVAL; Do you agree with this approach? Also, the use of mixed case was suggested by Andy to increase readability. ... > > > Best regards, > Matteo Martelli With Best Regards, Duicu Victor
