Re: [PATCH 4.19 04/74] ARM: dts: rockchip: Mark that the rk3288 timer might stop in suspend

[Pavel Machek]

On Mon 2019-08-05 15:02:17, Greg Kroah-Hartman wrote:
> [ Upstream commit 8ef1ba39a9fa53d2205e633bc9b21840a275908e ]
> 
> This is similar to commit e6186820a745 ("arm64: dts: rockchip: Arch
> counter doesn't tick in system suspend").  Specifically on the rk3288
> it can be seen that the timer stops ticking in suspend if we end up
> running through the "osc_disable" path in rk3288_slp_mode_set().  In
> that path the 24 MHz clock will turn off and the timer stops.
> 
> To test this, I ran this on a Chrome OS filesystem:
>   before=$(date); \
>   suspend_stress_test -c1 --suspend_min=30 --suspend_max=31; \
>   echo ${before}; date
> 
> ...and I found that unless I plug in a device that requests USB wakeup
> to be active that the two calls to "date" would show that fewer than
> 30 seconds passed.
> 
> NOTE: deep suspend (where the 24 MHz clock gets disabled) isn't
> supported yet on upstream Linux so this was tested on a downstream
> kernel.

I guess this does no harm, but deep sleep is unlikely to be suppored
in the stable kernels, so ... is it good idea there?

Thanks,
								Pavel

> --- a/arch/arm/boot/dts/rk3288.dtsi
> +++ b/arch/arm/boot/dts/rk3288.dtsi
> @@ -227,6 +227,7 @@
>  			     <GIC_PPI 11 (GIC_CPU_MASK_SIMPLE(4) | IRQ_TYPE_LEVEL_HIGH)>,
>  			     <GIC_PPI 10 (GIC_CPU_MASK_SIMPLE(4) | IRQ_TYPE_LEVEL_HIGH)>;
>  		clock-frequency = <24000000>;
> +		arm,no-tick-in-suspend;
>  	};
>  
>  	timer: timer@ff810000 {

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