linux-kernel - Re: [PATCH 5/9] ARM: dts: exynos: move exynos-bus nodes out of soc in Exynos4412

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Date:   Fri, 3 Feb 2023 21:34:09 +0100
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Marek Szyprowski <m.szyprowski@...sung.com>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Alim Akhtar <alim.akhtar@...sung.com>,
        Kukjin Kim <kgene@...nel.org>, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-samsung-soc@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     replicant@...osl.org, phone-devel@...r.kernel.org,
        ~postmarketos/upstreaming@...ts.sr.ht,
        Martin Jücker <martin.juecker@...il.com>,
        Henrik Grimler <henrik@...mler.se>,
        Chanwoo Choi <cw00.choi@...sung.com>
Subject: Re: [PATCH 5/9] ARM: dts: exynos: move exynos-bus nodes out of soc in
 Exynos4412

On 03/02/2023 12:51, Marek Szyprowski wrote:
> On 03.02.2023 12:46, Krzysztof Kozlowski wrote:
>> On 03/02/2023 12:45, Marek Szyprowski wrote:
>>> On 29.01.2023 11:42, Krzysztof Kozlowski wrote:
>>>> On 25/01/2023 10:45, Krzysztof Kozlowski wrote:
>>>>> The soc node is supposed to have only device nodes with MMIO addresses,
>>>>> as reported by dtc W=1:
>>>>>
>>>>>     exynos4412.dtsi:407.20-413.5:
>>>>>       Warning (simple_bus_reg): /soc/bus-acp: missing or empty reg/ranges property
>>>>>
>>>>> and dtbs_check:
>>>>>
>>>>>     exynos4412-i9300.dtb: soc: bus-acp:
>>>>>       {'compatible': ['samsung,exynos-bus'], 'clocks': [[7, 456]], 'clock-names': ['bus'], 'operating-points-v2': [[132]], 'status': ['okay'], 'devfreq': [[117]]} should not be valid under {'type': 'object'}
>>>>>
>>>>> Move the bus nodes and their OPP tables out of SoC to fix this.
>>>>> Re-order them alphabetically while moving and put some of the OPP tables
>>>>> in device nodes (if they are not shared).
>>>>>
>>>> Applied.
>>> I don't have a good news. It looks that this change is responsible for
>>> breaking boards that were rock-stable so far, like Odroid U3. I didn't
>>> manage to analyze what exactly causes the issue, but it looks that the
>>> exynos-bus devfreq driver somehow depends on the order of the nodes:
>>>
>>> (before)
>>>
>>> # dmesg | grep exynos-bus
>>> [    6.415266] exynos-bus: new bus device registered: soc:bus-dmc
>>> (100000 KHz ~ 400000 KHz)
>>> [    6.422717] exynos-bus: new bus device registered: soc:bus-acp
>>> (100000 KHz ~ 267000 KHz)
>>> [    6.454323] exynos-bus: new bus device registered: soc:bus-c2c
>>> (100000 KHz ~ 400000 KHz)
>>> [    6.489944] exynos-bus: new bus device registered: soc:bus-leftbus
>>> (100000 KHz ~ 200000 KHz)
>>> [    6.493990] exynos-bus: new bus device registered: soc:bus-rightbus
>>> (100000 KHz ~ 200000 KHz)
>>> [    6.494612] exynos-bus: new bus device registered: soc:bus-display
>>> (160000 KHz ~ 200000 KHz)
>>> [    6.494932] exynos-bus: new bus device registered: soc:bus-fsys
>>> (100000 KHz ~ 134000 KHz)
>>> [    6.495246] exynos-bus: new bus device registered: soc:bus-peri (
>>> 50000 KHz ~ 100000 KHz)
>>> [    6.495577] exynos-bus: new bus device registered: soc:bus-mfc
>>> (100000 KHz ~ 200000 KHz)
>>>
>>> (after)
>>>
>>> # dmesg | grep exynos-bus
>>>
>>> [    6.082032] exynos-bus: new bus device registered: bus-dmc (100000
>>> KHz ~ 400000 KHz)
>>> [    6.122726] exynos-bus: new bus device registered: bus-leftbus
>>> (100000 KHz ~ 200000 KHz)
>>> [    6.146705] exynos-bus: new bus device registered: bus-mfc (100000
>>> KHz ~ 200000 KHz)
>>> [    6.181632] exynos-bus: new bus device registered: bus-peri ( 50000
>>> KHz ~ 100000 KHz)
>>> [    6.204770] exynos-bus: new bus device registered: bus-rightbus
>>> (100000 KHz ~ 200000 KHz)
>>> [    6.211087] exynos-bus: new bus device registered: bus-acp (100000
>>> KHz ~ 267000 KHz)
>>> [    6.216936] exynos-bus: new bus device registered: bus-c2c (100000
>>> KHz ~ 400000 KHz)
>>> [    6.225748] exynos-bus: new bus device registered: bus-display
>>> (160000 KHz ~ 200000 KHz)
>>> [    6.242978] exynos-bus: new bus device registered: bus-fsys (100000
>>> KHz ~ 134000 KHz)
>>>
>>> This is definitely a driver bug, but so far it worked fine, so this is a
>>> regression that need to be addressed somehow...
>>
>> Thanks for checking, but what is exactly the bug? The devices registered
>> - just with different name.
> 
> The bug is that the board fails to boot from time to time, freezing 
> after registering PPMU counters...

My U3 with and without this patch, reports several warnings:
iommu_group_do_set_platform_dma()
exynos_iommu_domain_free()
clk_core_enable()

and finally:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:

and keeps stalling.

At least on next-20230203. Except all these (which anyway make board
unbootable) look fine around PMU and exynos-bus.

Best regards,
Krzysztof