Messages in this thread | | | From | Heiko Stübner <> | Subject | Re: [PATCH 7/9] clocksource/drivers/rockchip_timer: implement clocksource timer | Date | Thu, 24 Nov 2016 15:32:39 +0100 |
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Am Donnerstag, 24. November 2016, 17:14:56 schrieb Alexander Kochetkov: > > 24 нояб. 2016 г., в 16:21, Heiko Stübner <heiko@sntech.de> написал(а): > > > > what I actually meant was that the driver could also recognize the rk3188- > > timer compatible as "we need a clocksource" and it shouldn't matter which > > timer actually gets used for this. > > One rockchip timer cannot be used as clockevent and clocksource at the same > time. > > In case of clockevent we want interrupts from it at specified times. So we > load one value into timer counter and it generates an interrupt. > > In case of clocksource we load max value into timer counter, run timer and > read current value on demand. > > rockchip_timer driver currently implement clockevent. So, if I create only > one timer in the device tree, it should be clockevent timer. As that > behavior already expected from driver by people used it. > > I may suggest such solution here: if I want clocksource, I have to declare > two timer in device tree. First probed timer would be clockevent and second > one would be clocksource. All other timers will be ignored. Is that > solution good?
yep, sounds good, especially as with your patch 9/9 you already declare these necessary timers.
> If I want one timer and want it be clocksource not clockevent how that > situation should be configured? Device tree not good for this. Kconfig not > good. Pass that configuration on kernel command line?
simply ignore that case :-)
I.e. newer kernels are supposed to be able to run old devicetrees and in that case they will have the global-timer as (slightly unstable) clocksource.
Also on the cortex-a9 we also still have the smp-twd as clockevent device.
Heiko
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