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From: Thomas Gleixner <tglx@linutronix.de>
To: Alexander Kochetkov <al.kochet@gmail.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
	LAK <linux-arm-kernel@lists.infradead.org>,
	kernel@stlinux.com, Daniel Lezcano <daniel.lezcano@linaro.org>,
	Patrice Chotard <patrice.chotard@st.com>,
	Marc Zyngier <marc.zyngier@arm.com>,
	Mark Rutland <mark.rutland@arm.com>
Subject: Re: [PATCH] clocksource/arm_global_timer: reconfigure clockevents after cpufreq change
Date: Tue, 29 Nov 2016 15:09:46 +0100 (CET)	[thread overview]
Message-ID: <alpine.DEB.2.20.1611291508460.4358@nanos> (raw)
In-Reply-To: <2F6A5074-F54E-4B16-AB3D-DE7301E363FC@gmail.com>

[-- Attachment #1: Type: text/plain, Size: 1159 bytes --]

On Tue, 29 Nov 2016, Alexander Kochetkov wrote:
> > 29 нояб. 2016 г., в 16:42, Thomas Gleixner <tglx@linutronix.de> написал(а):
> > 
> > The frequency change would not only affect the clockevent device, it also
> > would affect the clocksource. So the patch is incomplete, but see below.
> Looks like kernel disallow change clocksource and shed_clock rate at
> runtime. I haven’t found any function for that.
> 
> > 29 нояб. 2016 г., в 16:42, Thomas Gleixner <tglx@linutronix.de> написал(а):
> > 
> > That's broken and the clk framework should keep the CORE_PERI clock at a
> > constant rate by reprogramming the divider of the CPU clock.
> 
> Thank you for the hint.
> 
> > Assumptions w/o real impact are a perfect reason not to apply that
> > patch. This want's a proper proof that the global timer really changes and
> > this hackery is required, which I seriously doubt.
> 
> It really changes. It changes like it changes for smp-twd. I guess they are
> driven by same clock CORE_PERI.

If that happens then the whole thing wants to be disabled on those
misconfigured systems and not just hacked for nothing.

Thanks,

	tglx

  reply	other threads:[~2016-11-29 14:12 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-11-29 12:15 [PATCH] clocksource/arm_global_timer: reconfigure clockevents after cpufreq change Alexander Kochetkov
2016-11-29 12:15 ` Alexander Kochetkov
2016-11-29 13:42   ` Thomas Gleixner
2016-11-29 14:05     ` Alexander Kochetkov
2016-11-29 14:09       ` Thomas Gleixner [this message]
2016-11-29 14:14     ` Marc Zyngier
2016-11-29 14:32       ` Thomas Gleixner
2016-11-29 14:51         ` Marc Zyngier
2016-11-29 15:04           ` Alexander Kochetkov
2016-11-29 14:51         ` Alexander Kochetkov
2016-11-29 15:07           ` Robin Murphy

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