On 31/03/2018 19:46, Paul Cercueil wrote: > Le 2018-03-31 10:10, Daniel Lezcano a écrit : >> On 29/03/2018 16:52, Paul Cercueil wrote: >>> >>> >>> Le mer. 28 mars 2018 à 18:25, Daniel Lezcano <daniel.lezcano@xxxxxxxxxx> >>> a écrit : >>>> On 28/03/2018 17:15, Paul Cercueil wrote: >>>>> Le 2018-03-24 07:26, Daniel Lezcano a écrit : >>>>>> On 18/03/2018 00:29, Paul Cercueil wrote: >>>>>>> This driver will use the TCU (Timer Counter Unit) present on the >>>>>>> Ingenic >>>>>>> JZ47xx SoCs to provide the kernel with a clocksource and timers. >>>>>> >>>>>> Please provide a more detailed description about the timer. >>>>> >>>>> There's a doc file for that :) >>>> >>>> Usually, when there is a new driver I ask for a description in the >>>> changelog for reference. >>>> >>>>>> Where is the clocksource ? >>>>> >>>>> Right, there is no clocksource, just timers. >>>>> >>>>>> I don't see the point of using channel idx and pwm checking here. >>>>>> >>>>>> There is one clockevent, why create multiple channels ? Can't you >>>>>> stick >>>>>> to the usual init routine for a timer. >>>>> >>>>> So the idea is that we use all the TCU channels that won't be used >>>>> for PWM >>>>> as timers. Hence the PWM checking. Why is this bad? >>>> >>>> It is not bad but arguable. By checking the channels used by the pwm in >>>> the code, you introduce an adherence between two subsystems even if it >>>> is just related to the DT parsing part. >>>> >>>> As it is not needed to have more than one timer in the time framework >>>> (at least with the same characteristics), the pwm channels check is >>>> pointless. We can assume the author of the DT file is smart enough to >>>> prevent conflicts and define a pwm and a timer properly instead of >>>> adding more code complexity. >>>> >>>> In addition, simplifying the code will allow you to use the timer-of >>>> code and reduce very significantly the init function. >>> >>> That's what I had in my V1 and V2, my DT node for the timer-ingenic >>> driver >>> had a "timers" property (e.g. "timers = <4 5>;") to select the channels >>> that >>> should be used as timers. Then Rob told me I shouldn't do that, and >>> instead >>> detect the channels that will be used for PWM. >>> >> >> [ ... ] >> >> How do you specify the channels used for PWM ? > > To detect the channels that will be used as PWM I parse the whole > devicetree > searching for "pwms" properties; check that the PWM handle is for our > TCU PWM > driver; then read the PWM number from there. > > Of course it's hackish, and it only works for devicetree. I preferred the > method with the "timers" property. Do you have a DT portion describing that? Eg somewhere in the kernel's git tree ?
