linux-kernel - Re: [PATCH] clocksource/arm_global_timer: reconfigure clockevents after cpufreq change

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Message-ID: <ecede3e0-2683-9cbb-1e27-e999a06fe4d7@arm.com>
Date:   Tue, 29 Nov 2016 15:07:54 +0000
From:   Robin Murphy <robin.murphy@....com>
To:     Alexander Kochetkov <al.kochet@...il.com>,
        Thomas Gleixner <tglx@...utronix.de>
Cc:     Mark Rutland <mark.rutland@....com>, kernel@...inux.com,
        Marc Zyngier <marc.zyngier@....com>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Patrice Chotard <patrice.chotard@...com>,
        LKML <linux-kernel@...r.kernel.org>,
        LAK <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH] clocksource/arm_global_timer: reconfigure clockevents
 after cpufreq change

On 29/11/16 14:51, Alexander Kochetkov wrote:
> 
>> 29 нояб. 2016 г., в 17:32, Thomas Gleixner <tglx@...utronix.de> написал(а):
>>
>> Can we just disable that global timer on affected SoCs and use something
>> else instead?
> 
> I’ve sent patch series for fixing that on rockchip SoC.
> http://lists.infradead.org/pipermail/linux-rockchip/2016-November/013217.html
> 
> But the series contain fix only for rk3188, because I don’t have another rockchip
> SoC. rk3288 and other could be easy fixed with dts files.

3288 (and probably anything newer) is irrelevant to this discussion, as
it has the arch timer interface - that may be busted in other ways (such
as not being correctly set up by firmware and not being always-on as it
should), but frequency is not one of them. This only affects
Cortex-A9/A5 based parts.

> There are a lot of other platforms what probably use shed_clock and
> clocksource form global-timer.

Presumably it's only an issue if they also have cpufreq?

> alexander@...ntu:dts$ grep arm,cortex-a9-global-timer *
> am4372.dtsi:		compatible = "arm,cortex-a9-global-timer";
> artpec6.dtsi:		compatible = "arm,cortex-a9-global-timer";
> bcm5301x.dtsi:			compatible = "arm,cortex-a9-global-timer";
> bcm63138.dtsi:			compatible = "arm,cortex-a9-global-timer";
> bcm-cygnus.dtsi:			compatible = "arm,cortex-a9-global-timer";
> bcm-nsp.dtsi:			compatible = "arm,cortex-a9-global-timer";
> hip01.dtsi:			compatible = "arm,cortex-a9-global-timer";
> rk3xxx.dtsi:		compatible = "arm,cortex-a9-global-timer";
> stih407-family.dtsi:		compatible = "arm,cortex-a9-global-timer";
> stih41x.dtsi:		compatible = "arm,cortex-a9-global-timer";
> uniphier-common32.dtsi:			compatible = "arm,cortex-a9-global-timer";
> uniphier-ph1-sld3.dtsi:			compatible = "arm,cortex-a9-global-timer";
> vexpress-v2p-ca5s.dts:		             "arm,cortex-a9-global-timer";

I can tell you that one, for one, is never used, because it depends on
an input clock provided by the vexpress-osc driver which cannot be
probed sufficiently early.

Robin.

> vf500.dtsi:				compatible = "arm,cortex-a9-global-timer";
> zx296702.dtsi:			compatible = "arm,cortex-a9-global-timer";
> zynq-7000.dtsi:			compatible = "arm,cortex-a9-global-timer»;
> 
> Regards,
> Alexander.
> 
> 
> _______________________________________________
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> linux-arm-kernel@...ts.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
> 

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