linux-kernel - Re: [PATCH V4 00/13] Add driver for dvfsrc, support for active state of scpsys

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Message-ID: <2737cc5c-3876-6861-c44f-fc9f552bbdb9@linaro.org>
Date:   Wed, 1 Apr 2020 18:09:11 +0300
From:   Georgi Djakov <georgi.djakov@...aro.org>
To:     Henry Chen <henryc.chen@...iatek.com>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Viresh Kumar <vireshk@...nel.org>,
        Stephen Boyd <swboyd@...omium.org>,
        Ryan Case <ryandcase@...omium.org>,
        Mark Brown <broonie@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Nicolas Boichat <drinkcat@...gle.com>,
        Fan Chen <fan.chen@...iatek.com>,
        James Liao <jamesjj.liao@...iatek.com>,
        Arvin Wang <arvin.wang@...iatek.com>,
        Mike Turquette <mturquette@...aro.org>,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-pm@...r.kernel.org, srv_heupstream@...iatek.com
Subject: Re: [PATCH V4 00/13] Add driver for dvfsrc, support for active state
 of scpsys

Hi Henry,

On 3/13/20 11:34, Henry Chen wrote:
> The patchsets add support for MediaTek hardware module named DVFSRC
> (dynamic voltage and frequency scaling resource collector). The DVFSRC is
> a HW module which is used to collect all the requests from both software
> and hardware and turn into the decision of minimum operating voltage and
> minimum DRAM frequency to fulfill those requests.
> 
> So, This series is to implement the dvfsrc driver to collect all the
> requests of operating voltage or DRAM bandwidth from other device drivers
> likes GPU/Camera through 3 frameworks basically:
> 
> 1. interconnect framework: to aggregate the bandwidth
>    requirements from different clients
> 
> [1] https://patchwork.kernel.org/cover/10766329/
> 
> Below is the emi bandwidth map of mt8183. There has a hw module "DRAM scheduler"
> which used to control the throughput. The DVFSRC will collect forecast data
> of dram bandwidth from SW consumers(camera/gpu...), and according the forecast
> to change the DRAM frequency
> 
>            ICC provider         ICC Nodes
>                             ----          ----
>            ---------       |CPU |   |--->|VPU |
>   -----   |         |-----> ----    |     ----
>  |DRAM |--|DRAM     |       ----    |     ----
>  |     |--|scheduler|----->|GPU |   |--->|DISP|
>  |     |--|(EMI)    |       ----    |     ----
>  |     |--|         |       -----   |     ----
>   -----   |         |----->|MMSYS|--|--->|VDEC|
>            ---------        -----   |     ----
>              /|\                    |     ----
>               |change DRAM freq     |--->|VENC|
>            ----------               |     ----
>           |  DVFSR   |              |
>           |          |              |     ----
>            ----------               |--->|IMG |
>                                     |     ----
>                                     |     ----
>                                     |--->|CAM |
>                                           ----

It would be useful to also add the above diagram into the commit text of
patch 09/13. By doing so, it will be saved into the history, as cover letters
are discarded.

Thanks,
Georgi