Messages in this thread | | | From | Thomas Gleixner <> | Subject | Re: [PATCH] rtc: adapt allowed RTC update error | Date | Wed, 02 Dec 2020 23:08:38 +0100 |
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On Wed, Dec 02 2020 at 16:54, Jason Gunthorpe wrote: > On Wed, Dec 02, 2020 at 08:21:00PM +0100, Thomas Gleixner wrote: >> So it will not write immediately. It will run through at least one >> retry. > > Right, bascially this is scheduling a WQ to do sched_sync_hw_clock() > which will only call hrtimer_start() - seems like jsut calling > hrtimer_start instead of queue_work above would be equivilant
Something like that.
>> I don't think the timer should be canceled if the ntp_synced() state did >> not change. Otherwise every do_adtimex() call will cancel/restart >> it, which does not make sense. Lemme stare at it some more. > > That makes sense, being conditional on the STA_UNSYNC prior to doing > any hrtimer_start seems OK?
Yeah.
>> > Also x86 needs a touch, it already has RTC lib, no idea why it also >> > provides this old path too >> >> Because nobody had the stomach and/or cycles to touch it :) > > Hahaha yes.. I vaugely remember looking at this once.. > > Lets see: > > arch/x86/kernel/kvmclock.c: x86_platform.set_wallclock = kvm_set_wallclock; > arch/x86/kernel/x86_init.c: x86_platform.set_wallclock = set_rtc_noop; > arch/x86/xen/time.c: x86_platform.set_wallclock = xen_set_wallclock; > arch/x86/xen/time.c: x86_platform.set_wallclock = xen_set_wallclock; > All returns -ENODEV/EINVAL
You forgot to stare at the .get_wallclock() functions. That's the more interesting part, i.e. what's behind read_persistent_clock64().
> arch/x86/kernel/x86_init.c: .set_wallclock = mach_set_rtc_mmss, > This is already rtclib under drivers/rtc/rtc-mc146818-lib.c
That's the shared library function for setting the darn thing.
> I suppose the issue here is the rtclib driver only binds via PNP and > very old x86 systems won't have the PNP tables? It seems doable to > check for a PNP device after late init and manually create a > platform_device for the RTC
old crap, broken BIOSes and virt. Welcome to my wonderful world :)
> arch/x86/platform/intel-mid/intel_mid_vrtc.c: x86_platform.set_wallclock = vrtc_set_mmss; > This is also already in rtclib under rtc-mrst.c, and this is already > wired to create the rtc platform device during init > > So it is very close now to be able to delete all this for x86. Do you > know of something I've missed?
Just the above :)
>> > I wonder if the cmos path could be killed off under the dead HW >> > principle? >> >> Unfortunately that code path is not that dead on x86. You need to fix >> all the (ab)users first. :) > > Assuming x86 can be resolved as above, that leaves two 20 year old MIPS > platforms and the PPC list from before. ARM is gone compared to last > time I looked! Progress :)
Yeah. We're zooming in ....
Thanks,
tglx
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