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Message-ID: <aba1fcac-74b8-f370-ab45-312975da66e6@gmail.com>
Date: Mon, 9 Nov 2020 08:10:16 +0300
From: Dmitry Osipenko <digetx@...il.com>
To: Viresh Kumar <viresh.kumar@...aro.org>
Cc: Ulf Hansson <ulf.hansson@...aro.org>,
Thierry Reding <thierry.reding@...il.com>,
Jonathan Hunter <jonathanh@...dia.com>,
Alan Stern <stern@...land.harvard.edu>,
Peter Chen <Peter.Chen@....com>,
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Adrian Hunter <adrian.hunter@...el.com>,
Krzysztof Kozlowski <krzk@...nel.org>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Lee Jones <lee.jones@...aro.org>,
Uwe Kleine-König <u.kleine-koenig@...gutronix.de>,
Mauro Carvalho Chehab <mchehab@...nel.org>,
Rob Herring <robh+dt@...nel.org>,
Marek Szyprowski <m.szyprowski@...sung.com>,
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Subject: Re: [PATCH v1 00/30] Introduce core voltage scaling for NVIDIA
Tegra20/30 SoCs
09.11.2020 07:47, Dmitry Osipenko пишет:
> 09.11.2020 07:43, Viresh Kumar пишет:
>> On 08-11-20, 15:19, Dmitry Osipenko wrote:
>>> I took a detailed look at the GENPD and tried to implement it. Here is
>>> what was found:
>>>
>>> 1. GENPD framework doesn't aggregate performance requests from the
>>> attached devices. This means that if deviceA requests performance state
>>> 10 and then deviceB requests state 3, then framework will set domain's
>>> state to 3 instead of 10.
>>
>> It does. Look at _genpd_reeval_performance_state().
>>
>
> Thanks, I probably had a bug in the quick prototype and then overlooked
> that function.
>
If a non-hardware device-tree node is okay to have for the domain, then
I can try again.
What I also haven't mentioned is that GENPD adds some extra complexity
to some drivers (3d, video decoder) because we will need to handle both
new GENPD and legacy Tegra specific pre-genpd era domains.
I'm also not exactly sure how the topology of domains should look like
because Tegra has a power-controller (PMC) which manages power rail of a
few hardware units. Perhaps it should be
device -> PMC domain -> CORE domain
but not exactly sure for now.
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