Hi On Thu, 31 Aug 2023 at 01:02, Guenter Roeck <linux@xxxxxxxxxxxx> wrote: > > On 8/30/23 12:14, Naresh Solanki wrote: > > Hi > > > [ ... ] > >>> + /* > >>> + * Calculate voltage from ADC value and MON range. > >>> + * ddata->mon_rng holds the voltage corresponding to the maximum value the > >>> + * 10-bit ADC can measure. > >>> + * To obtain the output, multiply the ADC value by the MON range (in > >>> + * microvolts) and then divide it by the maximum value of the 10-bit ADC. > >>> + */ > >>> + *val = mul_u64_u32_shr(*val, ddata->mon_rng[channel], 10); > >> > >> Why do you use mul_u64_u32_shr() here but a direct shift above ? > > There is possibility of overflow due to large value of ddata->mon_rng > > Does the right shift guarantee that the result fits into 32 bit ? Yes. Value in ddata->mon_rng can go upto 26bits, & ADC is 10 bit. The 10 bit right shift(part of calculation) makes sure the result never exceed 32 bit Regards, Naresh > > Thanks, > Guenter >
