From: Alexander Holler <holler@ahsoftware.de>
To: John Stultz <john.stultz@linaro.org>, John Whitmore <arigead@gmail.com>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Alessandro Zummo <a.zummo@towertech.it>
Subject: Re: rtc/hctosys.c Problem during kernel boot
Date: Thu, 12 Jun 2014 14:01:46 +0200 [thread overview]
Message-ID: <539996AA.6020205@ahsoftware.de> (raw)
In-Reply-To: <CANcMJZDqAmdFLYq2LW60zU_d05Pv8tcYE1Nb=ftZcj5UukxqaA@mail.gmail.com>
Am 12.06.2014 01:53, schrieb John Stultz:
> Sigh. Yea, this issue was brought up previously, but we never got
> around to a solution that could be merged.
>
> Basically hctosys is late_init, but if the driver is a module, it
> might not be loaded in time. Adding hooks at module load time when
> RTCs are registered could be done, but then you have the issue that
> userspace might have set the clock via something like ntpdate, so
> HCTOSYS could then cause the clock to be less accurate.
>
> So we need to make the HCTOSYS functionality happen at RTC register
> time, but it needs to set the clock only if nothing has set the clock
> already. This requires a new timekeeeping interface - something like
> timekeeping_set_time_if_unset(), which atomically would set the time
> if it has never been set.
>
> You can read some of the previous discussion here:
> https://lkml.org/lkml/2013/6/17/533
>
> I'd be very interested in patches to resolve this!
Hmm, I'm still using this patches, now with 3.15 on a bunch of very
different x86 and arm boxes. So they are now tested since a year.
Unfortunately my expieriences with Linux kernel maintainers became even
worse and I'm not very eager to post patches. But if someone wants these
patches based on 3.15, feel free to notice me.
To get rid of hctosys, I have 3 patches, and 2 more to implement
rtc_read_timeval() for higher resolution clocks.
Regards,
Alexander Holler
next prev parent reply other threads:[~2014-06-12 12:23 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-11 23:01 rtc/hctosys.c Problem during kernel boot John Whitmore
2014-06-11 23:53 ` John Stultz
2014-06-12 1:06 ` John Whitmore
2014-06-12 12:01 ` Alexander Holler [this message]
2014-06-12 13:15 ` Alessandro Zummo
2014-06-13 4:13 ` [PATCH 1/3] RFC: timekeeping: introduce flag systime_was_set Alexander Holler
2014-06-13 4:13 ` [PATCH 2/3] RFC: timekeeping: rtc: Introduce new kernel parameter hctosys Alexander Holler
2014-06-13 4:13 ` [PATCH 3/3] RFC: timekeeping: rtc: remove CONFIG_RTC_HCTOSYS and RTC_HCTOSYS_DEVICE Alexander Holler
2014-06-21 13:08 ` rtc/hctosys.c Problem during kernel boot Alexander Holler
2014-06-21 13:21 ` Alessandro Zummo
2014-06-23 21:36 ` John Stultz
2014-06-24 5:37 ` Alexander Holler
2014-06-27 8:47 ` Alexander Holler
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