linux-kernel - Re: [PATCH v6 0/7] MediaTek DVFSRC Bus Bandwidth and Regulator knobs

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Message-ID: <CAL_Jsq+F_pwhVLD1HF7=sYLp2w5kpc53UmzzffxyKzwh8WZthw@mail.gmail.com>
Date: Fri, 11 Oct 2024 17:15:05 -0500
From: Rob Herring <robh@...nel.org>
To: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
Cc: djakov@...nel.org, krzysztof.kozlowski+dt@...aro.org, conor+dt@...nel.org, 
	matthias.bgg@...il.com, lgirdwood@...il.com, broonie@...nel.org, 
	keescook@...omium.org, gustavoars@...nel.org, henryc.chen@...iatek.com, 
	linux-pm@...r.kernel.org, devicetree@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, 
	linux-mediatek@...ts.infradead.org, kernel@...labora.com, wenst@...omium.org, 
	amergnat@...libre.com
Subject: Re: [PATCH v6 0/7] MediaTek DVFSRC Bus Bandwidth and Regulator knobs

On Mon, Jun 10, 2024 at 3:57 AM AngeloGioacchino Del Regno
<angelogioacchino.delregno@...labora.com> wrote:
>
> Changes in v6:
>  - Fixed build with clang (thanks Nathan!)
>  - Removed unused mtk_rmw() macro in mtk-dvfsrc.c
>  - Added MODULE_DESCRIPTION() to mtk-dvfsrc-regulator.c
>
> Changes in v5:
>  - Fixed Kconfig dependencies in interconnect
>  - Fixed module build for dvfsrc and interconnect
>
> Changes in v4:
>  - Updated patch [3/7] to actually remove address/size cells
>    as the old version got unexpectedly pushed in v3.
>
> Changes in v3:
>  - Removed examples from interconnect and regulator bindings
>    and kept example node with interconnect and regulator in
>    the main DVFSRC binding as suggested
>  - Removed 'reg' from interconnect and regulator, removed both
>    address and size cells from the main DVFSRC binding as that
>    was not really needed
>  - Added anyOf-required entries in the regulator binding as it
>    doesn't make sense to probe it without any regulator subnode
>
> Changes in v2:
>  - Fixed issues with regulator binding about useless quotes and
>    wrong binding path (oops)
>  - Removed useless 'items' from DVFSRC main binding
>  - Allowed address/size cells to DVFSRC main binding to resolve
>    validation issues on the regulator and interconnect bindings
>  - Changed dvfsrc node name to `system-controller`, as the DVFSRC
>    is actually able to control multiple system components.
>  - Added a commit to remove mtk-dvfs-regulator.c before adding the
>    new, refactored regulator driver
>
>
> This series adds support for the MediaTek Dynamic Voltage and Frequency
> Scaling Resource Controller (DVFSRC), found on many MediaTek SoCs.
>
> This hardware collects requests from both software and the various remote
> processors embededd into the SoC, and decides about a minimum operating
> voltage and a minimum DRAM frequency to fulfill those requests, in an
> effort to provide the best achievable performance per watt.
>
> Such hardware IP is capable of transparently performing direct register
> R/W on all of the DVFSRC-controlled regulators and SoC bandwidth knobs.
>
> Summarizing how the DVFSRC works for Interconnect:
>
>              ICC provider         ICC Nodes
>                               ----          ----
>              _________       |CPU |   |--- |VPU |
>     _____   |         |-----  ----    |     ----
>    |     |->|  DRAM   |       ----    |     ----
>    |DRAM |->|scheduler|----- |GPU |   |--- |DISP|
>    |     |->|  (EMI)  |       ----    |     ----
>    |_____|->|_________|---.   -----   |     ----
>                /|\         `-|MMSYS|--|--- |VDEC|
>                 |             -----   |     ----
>                 |                     |     ----
>                 | change DRAM freq    |--- |VENC|
>              --------                 |     ----
>     SMC --> | DVFSRC |                |     ----
>              --------                 |--- |IMG |
>                                       |     ----
>                                       |     ----
>                                       |--- |CAM |
>                                             ----
>
> ...and for regulators, it's simply...
>    SMC -> DVFSRC -> Regulator voltage decider -> (vreg) Registers R/W
>
> Please note that this series is based on an old (abandoned) series from
> MediaTek [1], and reuses some parts of the code found in that.
>
> Besides, included in this series, there's also a refactoring of the
> mtk-dvfsrc-regulator driver, which never got compiled at all, and would
> not build anyway because of missing headers and typos: that commit did
> not get any Fixes tag because, well, backporting makes no sense at all
> as the DVFSRC support - which is critical for that driver to work - is
> introduced with *this series*! :-)
>
> P.S.: The DVFSRC regulator is a requirement for the MediaTek UFSHCI
>       controller's crypto boost feature, which is already upstream but
>       lacking the actual regulator to work....... :-)
>
> [1]: https://lore.kernel.org/all/20210812085846.2628-1-dawei.chien@mediatek.com/
>
> AngeloGioacchino Del Regno (7):
>   dt-bindings: regulator: Add bindings for MediaTek DVFSRC Regulators
>   dt-bindings: interconnect: Add MediaTek EMI Interconnect bindings
>   dt-bindings: soc: mediatek: Add DVFSRC bindings for MT8183 and MT8195
>   soc: mediatek: Add MediaTek DVFS Resource Collector (DVFSRC) driver

Looks like the driver got picked up, but not the binding.
mediatek,mt8183-dvfsrc and mediatek,mt8195-dvfsrc show up in next as
undocumented.

Rob