Messages in this thread Patch in this message | | | From | Nicolai Stange <> | Subject | [PATCH] x86/uv/time: set ->min_delta_ticks and ->max_delta_ticks | Date | Thu, 30 Mar 2017 22:04:58 +0200 |
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In preparation for making the clockevents core NTP correction aware, all clockevent device drivers must set ->min_delta_ticks and ->max_delta_ticks rather than ->min_delta_ns and ->max_delta_ns: a clockevent device's rate is going to change dynamically and thus, the ratio of ns to ticks ceases to stay invariant.
Currently, the x86's uv rtc clockevent device is initialized as follows:
clock_event_device_uv.min_delta_ns = NSEC_PER_SEC / sn_rtc_cycles_per_second; clock_event_device_uv.max_delta_ns = clocksource_uv.mask * (NSEC_PER_SEC / sn_rtc_cycles_per_second);
This translates to a ->min_delta_ticks value of 1 and a ->max_delta_ticks value of clocksource_uv.mask.
Initialize ->min_delta_ticks and ->max_delta_ticks with these values respectively.
This patch alone doesn't introduce any change in functionality as the clockevents core still looks exclusively at the (untouched) ->min_delta_ns and ->max_delta_ns. As soon as this has changed, a followup patch will purge the initialization of ->min_delta_ns and ->max_delta_ns from this driver.
Signed-off-by: Nicolai Stange <nicstange@gmail.com> ---
Notes: This prerequisite patch is part of a larger effort to feed NTP corrections into the clockevent devices' frequencies and thus avoiding their notion of time to diverge from the system's one. If you're interested, the current state of the whole series can be found at [1]. If you haven't got any objections and these prerequisites get merged by 4.12 everywhere, I'll proceed with the remainder of this series in 4.13. Applicable to next-20170324 as well as to John' Stultz tree [2]. [1] git://nicst.de/linux.git cev-freq-adj.v10.fortglx-4.12-time https://nicst.de/git/?p=linux.git;a=shortlog;h=refs/heads/cev-freq-adj.v10.fortglx-4.12-time [2] https://git.linaro.org/people/john.stultz/linux.git fortglx/4.12/time
arch/x86/platform/uv/uv_time.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/arch/x86/platform/uv/uv_time.c b/arch/x86/platform/uv/uv_time.c index 2ee7632d4916..b082d71b08ee 100644 --- a/arch/x86/platform/uv/uv_time.c +++ b/arch/x86/platform/uv/uv_time.c @@ -390,9 +390,11 @@ static __init int uv_rtc_setup_clock(void) clock_event_device_uv.min_delta_ns = NSEC_PER_SEC / sn_rtc_cycles_per_second; + clock_event_device_uv.min_delta_ticks = 1; clock_event_device_uv.max_delta_ns = clocksource_uv.mask * (NSEC_PER_SEC / sn_rtc_cycles_per_second); + clock_event_device_uv.max_delta_ticks = clocksource_uv.mask; rc = schedule_on_each_cpu(uv_rtc_register_clockevents); if (rc) { -- 2.12.0
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