Message-ID: <b3f31e71-fa1a-e0c0-fdfa-f65674ccc5cd@samsung.com>
Date:   Fri, 3 Feb 2023 12:45:09 +0100
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Subject: Re: [PATCH 5/9] ARM: dts: exynos: move exynos-bus nodes out of soc
 in Exynos4412
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To:     Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Alim Akhtar <alim.akhtar@samsung.com>,
        Kukjin Kim <kgene@kernel.org>, devicetree@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org,
        linux-samsung-soc@vger.kernel.org, linux-kernel@vger.kernel.org
Cc:     replicant@osuosl.org, phone-devel@vger.kernel.org,
        ~postmarketos/upstreaming@lists.sr.ht,
        =?UTF-8?Q?Martin_J=c3=bccker?= <martin.juecker@gmail.com>,
        Henrik Grimler <henrik@grimler.se>,
        Chanwoo Choi <cw00.choi@samsung.com>
From:   Marek Szyprowski <m.szyprowski@samsung.com>
In-Reply-To: <29841f64-360b-1426-e1fd-dd4c64ee5455@linaro.org>
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References: <20230125094513.155063-1-krzysztof.kozlowski@linaro.org>
        <20230125094513.155063-5-krzysztof.kozlowski@linaro.org>
        <CGME20230129104220eucas1p15b70f73be86fa5600cfe170d22869836@eucas1p1.samsung.com>
        <29841f64-360b-1426-e1fd-dd4c64ee5455@linaro.org>
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Hi Krzysztof,

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...

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland