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Message-ID: <3c3c80da-8986-4a8b-8b53-c33b36107e95@linaro.org>
Date:   Tue, 10 Oct 2023 23:17:34 +0200
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Subject: Re: [PATCH v5 4/4] ARM: dts: qcom: ipq8064: Add CPU OPP table
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To:     Christian Marangi <ansuelsmth@gmail.com>
Cc:     Robert Marko <robimarko@gmail.com>, ilia.lin@kernel.org,
        vireshk@kernel.org, nm@ti.com, sboyd@kernel.org,
        robh+dt@kernel.org, krzysztof.kozlowski+dt@linaro.org,
        conor+dt@kernel.org, agross@kernel.org, andersson@kernel.org,
        rafael@kernel.org, linux-pm@vger.kernel.org,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-arm-msm@vger.kernel.org
References: <20230930102218.229613-1-robimarko@gmail.com>
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 <6525ad59.1c0a0220.e3509.8545@mx.google.com>
From:   Konrad Dybcio <konrad.dybcio@linaro.org>
In-Reply-To: <6525ad59.1c0a0220.e3509.8545@mx.google.com>
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On 10/10/23 22:00, Christian Marangi wrote:
> On Tue, Oct 10, 2023 at 09:52:50PM +0200, Konrad Dybcio wrote:
>>
>>
>> On 10/10/23 16:15, Christian Marangi wrote:
>>> On Tue, Oct 10, 2023 at 03:40:32PM +0200, Konrad Dybcio wrote:
>>>>
>>>>
>>>> On 9/30/23 12:21, Robert Marko wrote:
>>>>> From: Christian Marangi <ansuelsmth@gmail.com>
>>>>>
>>>>> Add CPU OPP table for IPQ8062, IPQ8064 and IPQ8065 SoC.
>>>>> Use opp-supported-hw binding to correctly enable and disable the
>>>>> frequency as IPQ8062 supports up to 1.0Ghz, IPQ8064 supports up to
>>>>> 1.4GHz with 1.2GHz as an additional frequency and IPQ8065 supports
>>>>> 1.7GHZ but doesn't have 1.2GHZ frequency and has to be disabled.
>>>>>
>>>>> Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
>>>>> Signed-off-by: Robert Marko <robimarko@gmail.com>
>>>>> ---
>>>> Christian/Robert, can you provide a downstream source for this?
>>>>
>>>
>>> Sure, consider that everything is with +/-5%.
>> Hm, so you're e.g. putting ipq8062 384MHz voltage for PVS3 equal to
>> 0.95*800000 = 760000, but I'm not sure if it's a good idea?
>>
>> The comment in downstream:
>>
>> "These are based on +/-5% Margin on the VDD_APCx that is advertised in our
>> Datasheet across Temperature"
>>
>> suggests this is already not very accurate, and betting that the lower
>> threshold works on all chips is probably not the best idea.
>>
> 
> Consider that everything is driven by the rpm. The original qsdk used the
> same approach of taking the value, apply +-5% and pass it as a voltage
> triplet to the rpm regulator. Also the driver have ranges so it
> autodecide the best voltage in the range of the voltage triplet based on
> the one supported by the regulator. Normally the normal voltage is
> always used.
Eeh? So you pass any half-random value to it and RPM edits it in flight?

Please be more specific, I'm not very familiar with this platform

Konrad