On Mon, Mar 09, 2020 at 12:35:06PM -0700, Guru Das Srinagesh wrote: > Because period and duty cycle are defined in the PWM framework structs > as ints with units of nanoseconds, the maximum time duration that can be > set is limited to ~2.147 seconds. Redefining them as u64 values will > enable larger time durations to be set. > > As a first step, prepare drivers to handle the switch to u64 period and > duty_cycle by replacing division operations involving pwm period and duty cycle > with their 64-bit equivalents as appropriate. The actual switch to u64 period > and duty_cycle follows as a separate patch. > > Where the dividend is 64-bit but the divisor is 32-bit, use *_ULL > macros: > - DIV_ROUND_UP_ULL > - DIV_ROUND_CLOSEST_ULL > - div_u64 > > Where the divisor is 64-bit (dividend may be 32-bit or 64-bit), use > DIV64_* macros: > - DIV64_U64_ROUND_CLOSEST > - div64_u64 > There is no explanation why this is necessary. What is the use case ? It is hard to imagine a real-world use case with a duty cycle of more than 2 seconds. Guenter
