On 31/07/2018 00:01, Paul Cercueil wrote: [ ... ] >>> +- ingenic,timer-channel: Specifies the TCU channel that should be >>> used as >>> + system timer. If not provided, the TCU channel 0 is used for the >>> system timer. >>> + >>> +- ingenic,clocksource-channel: Specifies the TCU channel that >>> should be used >>> + as clocksource and sched_clock. It must be a different channel >>> than the one >>> + used as system timer. If not provided, neither a clocksource nor a >>> + sched_clock is instantiated. >> >> clocksource and sched_clock are Linux specific and don't belong in DT. >> You should define properties of the hardware or use existing properties >> like interrupts or clocks to figure out which channel to use. For >> example, if some channels don't have an interrupt, then use them for >> clocksource and not a clockevent. Or you could have timers that run in >> low-power modes or not. If all the channels are identical, then it >> shouldn't matter which ones the OS picks. It can't work in this case because the pmw and the timer driver are not communicating and the first one can stole a channel to the last one. > We already talked about that. All the TCU channels can be used for PWM. > The problem is I cannot know from the driver's scope which channels will > be free and which channels will be requested for PWM. You suggested that I > parse the devicetree for clients, and I did that in the V3/V4 patchset. But > it only works for clients requesting through devicetree, not from platform > code or even sysfs. > > One thing I can try is to dynamically change the channels the system timer > and clocksource are using when the current ones are requested for PWM. But > that sounds hardcore... Yes, it is :/ Sorry for letting you wasting time and effort to write an overkill code not suitable for upstream. A very gross thought, wouldn't be possible to "register" a channel from the timer driver code in a shared data area (but well self-encapsulated) and the pwm code will check such channel isn't in use ? -- <http://www.linaro.org/> Linaro.org │ Open source software for ARM SoCs Follow Linaro: <http://www.facebook.com/pages/Linaro> Facebook | <http://twitter.com/#!/linaroorg> Twitter | <http://www.linaro.org/linaro-blog/> Blog
