Messages in this thread | | | Date | Fri, 18 May 2007 17:52:45 +0100 | From | Matt Sealey <> | Subject | Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver |
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Kumar Gala wrote: > > On May 18, 2007, at 9:48 AM, Thomas Gleixner wrote: > >> On Fri, 2007-05-18 at 15:28 +0100, Matt Sealey wrote: >>> >>> I think both the MPC52xx GPT0-7 and the SLT0-1 fulfil this fairly >>> easily. >> >> There is some basic work for MPC5200 available: >> >> http://www.pengutronix.de/oselas/bsp/phytec/index_en.html#phyCORE-MPC5200B-tiny >> > > I asked this earlier, but figured you might have a better insight. Is > their value in having 'drivers' for more than one clock source? I'd say > most (of not all) the PPC SoCs have timers on the system side that we > could provide drivers for, I'm just not sure if that does anything for > anyone.
As I asked after, I'm also very intrigued as to what is going to end up using these timers, but likewise, not much use writing a driver if everyone can use the extremely high resolution decrementer all at once..
As I said before too, at least Intel has decided there is a great need for up to 256 high resolution timer sources on a system, but since this is a fairly new concept to Linux (and hrtimers and dynticks too) it only seems to be used in the case of i8254/RTC emulation, mostly on x86-64.
I'm looking at it now and finding "users" of hrtimers is looking very thin on the ground. Maybe it's justified on the basis that more is better, and having support is preferable to not having it (even if nobody really uses it) but it seems the entire gamut of timing possibility in Linux can be handled through a simple, and single, high resolution timer and a queue of events..
So do we need some more? :D
-- Matt Sealey <matt@genesi-usa.com> Genesi, Manager, Developer Relations - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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