linux-kernel - Re: [PATCH v5 1/9] arm64: dts: exynos: Add dts files for 64-bit Exynos5433 SoC

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Message-id: <54F99B1A.3080600@samsung.com>
Date:	Fri, 06 Mar 2015 21:18:34 +0900
From:	Chanwoo Choi <cw00.choi@...sung.com>
To:	Mark Rutland <mark.rutland@....com>
Cc:	Chanwoo Choi <cwchoi00@...il.com>,
	"kgene@...nel.org" <kgene@...nel.org>,
	Marc Zyngier <Marc.Zyngier@....com>,
	"arnd@...db.de" <arnd@...db.de>, "olof@...om.net" <olof@...om.net>,
	Catalin Marinas <Catalin.Marinas@....com>,
	Will Deacon <Will.Deacon@....com>,
	"inki.dae@...sung.com" <inki.dae@...sung.com>,
	"chanho61.park@...sung.com" <chanho61.park@...sung.com>,
	"sw0312.kim@...sung.com" <sw0312.kim@...sung.com>,
	"jh80.chung@...sung.com" <jh80.chung@...sung.com>,
	"ideal.song@...sung.com" <ideal.song@...sung.com>,
	"a.kesavan@...sung.com" <a.kesavan@...sung.com>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-samsung-soc@...r.kernel.org" 
	<linux-samsung-soc@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v5 1/9] arm64: dts: exynos: Add dts files for 64-bit
 Exynos5433 SoC

Hi,

On 03/06/2015 08:40 PM, Mark Rutland wrote:
>>>>>> CPU0 (boot CPU) is only well working for CPU_OFF.
>>>>>> But when I try to turn on the CPU0 after CPU_OFF, I failed it.
>>>>>
>>>>> That's rather worrying. Can you look into what's going on here? I'd
>>>>> rather not have dts describing things which are known to be broken.
>>>>
>>>> The board dts don't include any node for CPU_ON/OFF.
>>>
>>> I don't understand. The CPU_ON and CPU_OFF IDs are in the psci node
>>> quoted above, and all the CPUs had enable-method = "psci".
>>
>> I mean that there are not additional dt node except for 'cpu' and 'psci' node.
> 
> The psci node and cpu enable-method are sufficient. No other nodes
> should be relevant.

You're right.

> 
>>>
>>>> When I try to turn on the CPU0 (boot CPU), fail to turn on and lockup happen.
>>>> After lockup happen, I cannot use the console.
>>>
>>> That sounds like a pretty major bug.
>>>
>>> Are you able to investigate with a hardware debugger?
>>
>> I can't do because there are not any jtag connector.
> 
> That is very unfortunate. Which PSCI implementation are you using?
> Surely whoever developed it has access to debug. Surely they should have
> tested this?

I just used the lateset Linux 4.0-rc2 for PSCI (arch/arm64/kernel/psci.c)
without any modification. Unfortunately, I don't know who is the h/w developer of Exynos5433 SoC.

> 
>>> Do other CPUs eventually log errors regarding the lockup? Or is the
>>> machine completely dead from this point on?
>>
>> I tested CPU0 on/off. When I turn on the CPU0, I fail it. But, kernel just show the error log without lockup.
>> I gave you wrong infromation about CPU0 off.
> 
> Ok. However that's still a major bug.
> 
> [...]
> 
>>>>>>> I take it CPUs boot at EL2?
>>>>>
>>>>> Do the CPUs boot at EL1 or EL2?
>>>>
>>>> Unfortunately, I cannot check the secure firmware for Exynos5433 SoC.
>>>> I think that a few SoC provider probably would know it.
>>>
>>> I guess I asked the wrong question.
>>>
>>> Do CPUs enter the kernel at EL2 or at EL1?
>>
>> Could you give me a tip how to check the kernel at EL2 or EL1?
> 
> Hmm... I thought we logged this but it looks like we don't.
> 
> You could hack in a check of is_hyp_mode_available() and
> is_hyp_mode_mismatched(). That will tell you if EL2/hyp is available,
> and whether all CPUs enter at the same mode (mandatory per the boot
> protocol).

OK, I'll try it.

Thanks,
Chanwoo Choi

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