linux-kernel - Re: [PATCH V7 0/2] qcom: x1e80100: Enable CPUFreq

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Message-ID: <0fd14fb1-736d-cf7f-128f-658bda0de583@quicinc.com>
Date: Thu, 5 Dec 2024 16:53:05 +0530
From: Sibi Sankar <quic_sibis@...cinc.com>
To: Marc Zyngier <maz@...nel.org>, Johan Hovold <johan@...nel.org>
CC: <sudeep.holla@....com>, <cristian.marussi@....com>, <andersson@...nel.org>,
        <konrad.dybcio@...aro.org>, <robh+dt@...nel.org>,
        <krzysztof.kozlowski+dt@...aro.org>, <dmitry.baryshkov@...aro.org>,
        <linux-kernel@...r.kernel.org>, <linux-arm-msm@...r.kernel.org>,
        <devicetree@...r.kernel.org>, <quic_rgottimu@...cinc.com>,
        <quic_kshivnan@...cinc.com>, <conor+dt@...nel.org>,
        <quic_nkela@...cinc.com>, <quic_psodagud@...cinc.com>,
        <abel.vesa@...aro.org>
Subject: Re: [PATCH V7 0/2] qcom: x1e80100: Enable CPUFreq



On 11/5/24 23:42, Marc Zyngier wrote:
> On Tue, 05 Nov 2024 16:57:07 +0000,
> Johan Hovold <johan@...nel.org> wrote:
>>
>> On Fri, Nov 01, 2024 at 02:43:57PM +0000, Marc Zyngier wrote:
>>> On Fri, 01 Nov 2024 14:19:54 +0000,
>>> Johan Hovold <johan@...nel.org> wrote:
>>
>>>> The side-effects and these remaining warnings are addressed by this
>>>> series:
>>>>
>>>> 	https://lore.kernel.org/all/20241030125512.2884761-1-quic_sibis@quicinc.com/
>>>>
>>>> but I think we should try to make the warnings a bit more informative
>>>> (and less scary) by printing something along the lines of:
>>>>
>>>> 	arm-scmi arm-scmi.0.auto: [Firmware Bug]: Ignoring duplicate OPP 3417600 for NCC
>>>>
>>>> instead.
>>>
>>> Indeed. Seeing [Firmware Bug] has a comforting feeling of
>>> familiarity... :)
>>>
>>> I wonder whether the same sort of reset happen on more "commercial"
>>> systems (such as some of the laptops). You expect that people look at
>>> the cpufreq stuff closely, and don't see things exploding like we are.
>>
>> I finally got around to getting my Lenovo ThinkPad T14s to boot (it
>> refuses to start the kernel when using GRUB, and it's not due to the
>> known 64 GB memory issue as it only has 32 GB)
> 
> <cry>
> I know the feeling. My devkit can't use GRUB either, so I added a
> hook to the GRUB config to generate EFI scripts that directly execute
> the kernel with initrd, dtb, and command line.
> 
> This is probably the worse firmware I've seen in a very long while.

The PERF_LEVEL_GET implementation in the SCP firmware side
is the reason for the crash :|, currently there is a bug
in the kernel that picks up index that we set with LEVEL_SET
with fast channel and that masks the crash. I was told the
crash happens when idle states are enabled and a regular
LEVEL_GET message is triggered from the kernel. This was
fixed a while back but it will take a while to flow back
to all the devices. It should already be out CRD's.

Johan,
Now that you are aware of the the limitations can we make
a call on how to deal with this and land cpufreq?

-Sibi

> </cry>
> 
>> and can confirm that it
>> hard resets when accessing the cpufreq sysfs attributes as well.
> 
> Right. So this also happens on non-abandonware machines.
> 
>> On the bright side, at least I don't see any warnings due to duplicate
>> OPPs on this machine (x1e78100, latest UEFI fw).
> 
> One bug fixed...
> 
> 	M.
>