Messages in this thread | | | Date | Tue, 20 Nov 2018 20:30:09 +1100 (AEDT) | From | Finn Thain <> | Subject | Re: [RFC PATCH v2 07/14] m68k: atari: Convert to clocksource API |
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On Tue, 20 Nov 2018, Linus Walleij wrote:
> > Yes you already see the same as I see: this chip MK68901 has no less > than four timers. I bet the kernel is just using one of them, out of > habit. > > By just setting another timer as free-running we get a classic and clean > Linux clocksource for the Atari. >
These are all 8-bit timers. Whereas the smallest clocksource mask I can find with grep is 24-bits.
You can divide the oscillator down to 12288 Hz giving a maximum period of 20 ms. My concern would be that clocksource counter wrap could still go undetected given a little interrupt latency.
> This is however a very good start in untangling the mess (as is the > whole patch series). >
It should be exciting to see what happens when some of these changes get tested 8-) I've only seen results for Mac and Atari so far.
> As with the Amiga, this chip also has an RTC clock that should go to the > RTC subsystem, naturally. >
I think some Atari's have an MC146818, which is drivers/rtc/rtc-cmos.c, arch/alpha/kernel/rtc.c etc.
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> Yours, > Linus Walleij >
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