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Date: Fri, 31 May 2024 23:24:53 +0200
From: Dragan Simic <dsimic@manjaro.org>
To: Jonas Karlman <jonas@kwiboo.se>
Cc: Alexey Charkov <alchark@gmail.com>, linux-rockchip@lists.infradead.org,
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Subject: Re: [RFC PATCH] arm64: dts: rockchip: Make preparations for
 per-RK3588-variant OPPs
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Hello Jonas,

On 2024-05-31 13:27, Jonas Karlman wrote:
> On 2024-05-30 21:31, Dragan Simic wrote:
> [snip]
> 
>>>>>> That way we'll have no roadblocks if, at some point, we end up 
>>>>>> with
>>>>>> having
>>>>>> different OPPs defined for the RK3588 and the RK3588S variants.  
>>>>>> Or
>>>>>> maybe
>>>>>> even for the RK3582, which we don't know much about yet.
>>>>> 
>>>>> Guess we'll deal with that one once we stumble upon an actual 
>>>>> RK3582
>>>>> board out in the wild and heading to the mainline kernel tree :)
>>>> 
>>>> Of course, that was just an example for the future use.
>>> 
>>> In fact, I've just discovered that Radxa has recently released Rock 
>>> 5C
>>> Lite which is based on RK3582, and starts at just $29 for the 1GB
>>> version, making it interesting for tinkering. Especially given that
>>> its GPU, one of the big-core clusters and one of the VPU cores seem 
>>> to
>>> be disabled in software (u-boot) rather than in hardware, which means
>>> there is some chance that a particular SoC specimen would actually
>>> have them in a working condition and possible to re-enable at no 
>>> cost.
>>> Ordered myself one to investigate :)
>> 
>> Yes, I also saw the RK3582-based ROCK 5C Lite a couple of days ago. :)
>> It seems that the disabled IP blocks are detected as defective during
>> the manufacturing, which means that they might work correctly, or 
>> might
>> actually misbehave.  It seems similar to the way old three-core AMD
>> Phenom II CPUs could sometimes be made quad-core.
> 
> I can confirm that the RK3582 include ip-state in OTP indicating
> unusable cores, any unusable cpu core cannot be taken online and stalls
> Linux kernel a few extra seconds during boot.

Thanks for this confirmation!

> Started working on a patch for U-Boot to remove any broken cpu core
> and/or cluster nodes, similar to what vendor U-Boot does, adopted to
> work with a mainline DT for RK3588.

Nice, thanks for working on that. :)

> On one of my ROCK 5C Lite board one of the cpu cores is unusable, 
> U-Boot
> removes the related cpu cluster nodes. On another ROCK 5C Lite board 
> one
> rkvdec core is only marked unusable and all cpu cores can be taken
> online, U-Boot does nothing in this case. Guessing we should apply
> similar policy as vendor U-Boot and disable cores anyway.

Just checking, you're referring to disabling the rkvdec core only,
for the latter case?

> Following commit contains early work-in-progress and some debug output.
> 
> https://github.com/Kwiboo/u-boot-rockchip/commit/8cdf606e616baa36751f3b4adcfaefc781126c8c
> 
> Booting ROCK 5C Lite boards using U-Boot generic-rk3588_defconfig:
> 
> ROCK 5C Lite v1.1 (RK3582 with 1 bad cpu core):
> 
>   cpu-code: 3582
>   cpu-version: 08 10
>   data: fe 21
>   package: 11
>   specification: 01
>   ip-state: 10 00 00
>   bad-state: cpu core 4
> 
> ROCK 5C Lite v1.1 (RK3582 with 1 bad rkvdec core):
> 
>   cpu-code: 3582
>   cpu-version: 08 00
>   data: fe 21
>   package: 11
>   specification: 01
>   ip-state: 00 80 00
>   bad-state: rkvdec core 1

Thanks again for these nice details!