Re: [PATCH v5 4/4] ARM: dts: qcom: ipq8064: Add CPU OPP table

Konrad Dybcio
2023-10-10T21:17:48Z

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