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

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Date:   Thu, 2 Apr 2020 10:48:02 +0800
From:   Henry Chen <henryc.chen@...iatek.com>
To:     Georgi Djakov <georgi.djakov@...aro.org>
CC:     Mark Rutland <mark.rutland@....com>,
        Nicolas Boichat <drinkcat@...gle.com>,
        Mike Turquette <mturquette@...aro.org>,
        <srv_heupstream@...iatek.com>,
        James Liao <jamesjj.liao@...iatek.com>,
        Viresh Kumar <vireshk@...nel.org>, <linux-pm@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, Rob Herring <robh+dt@...nel.org>,
        "Stephen Boyd" <swboyd@...omium.org>,
        Fan Chen <fan.chen@...iatek.com>, <devicetree@...r.kernel.org>,
        Mark Brown <broonie@...nel.org>,
        Ryan Case <ryandcase@...omium.org>,
        Arvin Wang <arvin.wang@...iatek.com>,
        "Matthias Brugger" <matthias.bgg@...il.com>,
        <linux-mediatek@...ts.infradead.org>,
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH V4 00/13] Add driver for dvfsrc, support for active
 state of scpsys

Hi Georgi,

On Wed, 2020-04-01 at 18:09 +0300, Georgi Djakov wrote:
> 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.
OK, thanks.
> 
> Thanks,
> Georgi
> 
> _______________________________________________
> Linux-mediatek mailing list
> Linux-mediatek@...ts.infradead.org
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