Hello Guenter, On Mon, Mar 09, 2020 at 02:48:22PM -0700, Guenter Roeck wrote: > 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. When my Laptop is in suspend there is an LED that blinks with a period of approximately 5 seconds. (To be fair, the brightness is more a sinus than a rectangle, but still.) Best regards Uwe -- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | https://www.pengutronix.de/ |
