Messages in this thread | | | Date | Wed, 14 Dec 2011 10:47:24 -0800 | From | Andres Salomon <> | Subject | Re: IRQF_TIMER | IRQF_SHARED ? |
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On Wed, 14 Dec 2011 19:37:39 +0100 Jens Rottmann <JRottmann@LiPPERTEmbedded.de> wrote:
> Jens Rottmann schrieb: > > Andres Salomon schrieb: > >> Just loading cs5535-clockevt should start the periodic timer. > >> On my XO-1, IRQ 7 starts firing immediately. > > Hmm, no, doesn't work. :-| In /proc/interrupts IRQ 0 gets > > increased, not (in my case) IRQ 11. > > Update: I found that SMP-enabled kernels (like the generic one I was > using) do load cs5535-clockevt fine but ignore it and keep using the > pit timer instead.
Note that there are two subsystems at work here; clockevents and clocksource. cs5535-clockevt uses clockevents (despite being in drivers/clocksource/). For you to switch away from pit (via, /sys/devices/system/clocksource/clocksource0/current_clocksource), we'd have to implement cs5535_clocksource. Something that would be worth doing, but I haven't looked into it..
> > Responsible seems kernel/time/tick-common.c: tick_check_new_device() > /* > * If the cpu affinity of the device interrupt can not > * be set, ignore it. > */ > if (!irq_can_set_affinity(newdev->irq)) > goto out_bc; > > Looks like it has been that way for quite some time, maybe > cs5535-clockevt hasn't ever worked on SMP kernels.
I've only ever tested it on UP kernels. I didn't know SMP CS5536 boards existed. Gosh, I hope all of those cs5535 drivers that hadn't had their locking primitives tested aren't racy! ;)
> > If I turn off SMP, cs5535-clockevt replaces the pit timer and the > MFGPT IRQ starts firing just as you said - at least on 3.0.9. 3.2-rc5 > prefers to hang instead, looks like no timer events get generated. > Sigh. >
3.2-rc4 hung on my XO-1 due to a bug that's been fixed on rc5, but I haven't tested rc5 yet.
> I'll try to narrow it down tomorrow, but now I'm calling it a day. > > Cheers > Jens
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