linux-kernel - Re: [PATCH v4 5/9] ARM: dts: rockchip: disable arm-global-timer for rk3188

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Date:   Mon, 23 Jan 2017 17:14:22 +0100
From:   Heiko Stübner <heiko@...ech.de>
To:     Alexander Kochetkov <al.kochet@...il.com>
Cc:     linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-rockchip@...ts.infradead.org,
        Thomas Gleixner <tglx@...utronix.de>,
        Mark Rutland <mark.rutland@....com>,
        Rob Herring <robh+dt@...nel.org>,
        Russell King <linux@...linux.org.uk>,
        Caesar Wang <wxt@...k-chips.com>,
        Huang Tao <huangtao@...k-chips.com>,
        Daniel Lezcano <daniel.lezcano@...aro.org>
Subject: Re: [PATCH v4 5/9] ARM: dts: rockchip: disable arm-global-timer for rk3188

Am Dienstag, 29. November 2016, 19:14:48 CET schrieb Alexander Kochetkov:
> arm-global-timer can provide clockevents, clocksource and shed_clock. But
> on rk3188 platform it provide only clocksource and shed_clock. clockevents
> from  arm-global-timer is not used by kernel because there is another
> clockevent provider with higher rating (smp-twd).
> 
> My commit from the series implement clocksource and shed_clock using
> rockchip_timer. But sched clock from rk_timer is not selected by kernel
> due to lower frequency than arm-global-timer, and clocksource from
> rk_timer is not selected by kernel due to lower rating than
> arm-global-timer. And I don't want to increase clocksource rating
> because ratings greater 300 used for high frequency clocksources.
> 
> clocksource and shed_clock is quite unstable, because their rate depends
> on cpu frequency. So disable arm-global-timer and use clocksource and
> sched_clock from rockchip_timer.

That commit message is hard to understand in its entirety, but this last 
paragraph is essentially enough to describe the problem. So maybe you could 
shorten that somehow.


Heiko


> Signed-off-by: Alexander Kochetkov <al.kochet@...il.com>
> ---
>  arch/arm/boot/dts/rk3188.dtsi |    1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/arch/arm/boot/dts/rk3188.dtsi b/arch/arm/boot/dts/rk3188.dtsi
> index 0dc52fe..44da3d42 100644
> --- a/arch/arm/boot/dts/rk3188.dtsi
> +++ b/arch/arm/boot/dts/rk3188.dtsi
> @@ -546,6 +546,7 @@
> 
>  &global_timer {
>  	interrupts = <GIC_PPI 11 0xf04>;
> +	status = "disabled";
>  };
> 
>  &local_timer {