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

[Georgi Djakov]

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