linux-kernel - Re: [PATCH] arm64: dts: exynos: Fix reboot/poweroff issues on Exynos7

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Date:   Wed, 4 Nov 2020 22:14:48 +0100
From:   Paweł Chmiel <pawel.mikolaj.chmiel@...il.com>
To:     Krzysztof Kozlowski <krzk@...nel.org>
Cc:     kgene@...nel.org, alim.akhtar@...sung.com, robh+dt@...nel.org,
        a.kesavan@...sung.com, naveenkrishna.ch@...il.com,
        thomas.ab@...sung.com, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-samsung-soc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] arm64: dts: exynos: Fix reboot/poweroff issues on Exynos7

Hi

On 29.10.2020 18:50, Krzysztof Kozlowski wrote:
> On Wed, Oct 28, 2020 at 10:08:13PM +0100, Paweł Chmiel wrote:
>> In vendor sources for Exynos 7420, psci is not used to reboot or
>> poweroff device. Instead we should use syscon reboot/poweroff.
>> Previously it was not possible to poweroff (no syscon poweroff node) or
>> reboot (because it was handled by psci and this way is not working for
>> Exynos).
> 
> Do you want to say that PSCI cannot be used to power off or reboot?
Yes
> 
>>
>> Fixes: fb026cb65247 ("arm64: dts: Add reboot node for exynos7")
>> Fixes: b9024cbc937d ("arm64: dts: Add initial device tree support for exynos7")
>> Signed-off-by: Paweł Chmiel <pawel.mikolaj.chmiel@...il.com>
>> ---
>>  arch/arm64/boot/dts/exynos/exynos7.dtsi | 11 ++++++++++-
>>  1 file changed, 10 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/arm64/boot/dts/exynos/exynos7.dtsi b/arch/arm64/boot/dts/exynos/exynos7.dtsi
>> index 959918f4ca45..47d54c369d03 100644
>> --- a/arch/arm64/boot/dts/exynos/exynos7.dtsi
>> +++ b/arch/arm64/boot/dts/exynos/exynos7.dtsi
>> @@ -117,8 +117,10 @@ cpu_atlas3: cpu@3 {
>>  	};
>>  
>>  	psci {
>> -		compatible = "arm,psci-0.2";
>> +		compatible = "arm,psci";
> 
> Please explain how is it related to this issue? You onle mentioned
> a problem of lacking syscon-reboot node.
> 
>>  		method = "smc";
>> +		cpu_off = <0x84000002>;
>> +		cpu_on = <0xC4000003>;
> 
> The same question.
Thanks for feedback. I'll split this patch into two - one for inclusion
of exynos-syscon-restart.dtsi and second one fixing psci compatible (so
syscon-poweroff/restart will be working).
> 
>>  	};
>>  
>>  	soc: soc@0 {
>> @@ -552,6 +554,13 @@ pmu_system_controller: system-controller@...c0000 {
>>  			compatible = "samsung,exynos7-pmu", "syscon";
>>  			reg = <0x105c0000 0x5000>;
>>  
>> +			poweroff: syscon-poweroff {
>> +				compatible = "syscon-poweroff";
>> +				regmap = <&pmu_system_controller>;
>> +				offset = <0x330C>; /* PS_HOLD_CONTROL */
>> +				mask = <0x5200>; /* reset value */
>> +			};
>> +
> 
> Instead, please include arm/exynos-syscon-restart.dtsi.
Will do this.
> 
> Best regards,
> Krzysztof
>