linux-kernel - Re: [PATCH v2 03/19] dt-bindings: power: mediatek: Add bindings for MediaTek SCPSYS

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <c4480c9ea0822ae693ff6a501c073c365e983b83.camel@mediatek.com>
Date:   Tue, 19 Jul 2022 16:17:16 +0800
From:   Tinghan Shen <tinghan.shen@...iatek.com>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        Yong Wu <yong.wu@...iatek.com>, Joerg Roedel <joro@...tes.org>,
        Will Deacon <will@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Lee Jones <lee.jones@...aro.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>,
        MandyJH Liu <mandyjh.liu@...iatek.com>
CC:     <iommu@...ts.linux.dev>, <linux-mediatek@...ts.infradead.org>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <Project_Global_Chrome_Upstream_Group@...iatek.com>
Subject: Re: [PATCH v2 03/19] dt-bindings: power: mediatek: Add bindings for
 MediaTek SCPSYS

Hi Krzysztof,

On Fri, 2022-07-15 at 09:57 +0200, Krzysztof Kozlowski wrote:
> On 14/07/2022 14:28, Tinghan Shen wrote:
> > The System Control Processor System (SCPSYS) has several power
> > management related tasks in the system. Add the bindings for it.
> > 
> > Signed-off-by: Tinghan Shen <tinghan.shen@...iatek.com>
> > ---
> >  .../bindings/mfd/mediatek,scpsys.yaml         | 62 +++++++++++++++++++
> >  1 file changed, 62 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/mfd/mediatek,scpsys.yaml
> > 
> > diff --git a/Documentation/devicetree/bindings/mfd/mediatek,scpsys.yaml
> > b/Documentation/devicetree/bindings/mfd/mediatek,scpsys.yaml
> > new file mode 100644
> > index 000000000000..a8b9220f2f27
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/mfd/mediatek,scpsys.yaml
> > @@ -0,0 +1,62 @@
> > +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
> > +%YAML 1.2
> > +---
> > +$id: 
> > https://urldefense.com/v3/__http://devicetree.org/schemas/mfd/mediatek,scpsys.yaml*__;Iw!!CTRNKA9wMg0ARbw!1TUl-dhD0p8qh3rYVk8RtfoKEP88jg8OADMd19qP6siBCQHhFnHWCgsyUqiETyBzxw8$
> >  
> > +$schema: 
> > https://urldefense.com/v3/__http://devicetree.org/meta-schemas/core.yaml*__;Iw!!CTRNKA9wMg0ARbw!1TUl-dhD0p8qh3rYVk8RtfoKEP88jg8OADMd19qP6siBCQHhFnHWCgsyUqiEJQmakAI$
> >  
> > +
> > +title: MediaTek System Control Processor System
> > +
> > +maintainers:
> > +  - MandyJH Liu <mandyjh.liu@...iatek.com>
> > +
> > +description:
> > +  MediaTek System Control Processor System (SCPSYS) has several
> > +  power management tasks. The tasks include MTCMOS power
> > +  domain control, thermal measurement, DVFS, etc.
> > +
> > +properties:
> > +  compatible:
> > +    items:
> > +      - const: mediatek,scpsys
> > +      - const: syscon
> > +      - const: simple-mfd
> > +
> > +  reg:
> > +    maxItems: 1
> > +
> > +  power-controller:
> > +    $ref: /schemas/power/mediatek,power-controller.yaml#
> > +
> > +required:
> > +  - compatible
> > +  - reg
> > +
> > +additionalProperties: false
> > +
> > +examples:
> > +  - |
> > +    #include <dt-bindings/clock/mt8195-clk.h>
> > +    #include <dt-bindings/power/mt8195-power.h>
> > +
> > +    syscon@...06000 {
> > +        compatible = "mediatek,scpsys", "syscon", "simple-mfd";
> 
> This should be a SoC-specific compatible (and filename).

Ok. I think that you mean "mediatek,mt8195-scpsys".
I'll update it in next version.

> 
> > +        reg = <0x10006000 0x100>;
> > +
> > +        spm: power-controller {
> 
> I think you created before less-portable, quite constrained bindings for
> power controller. You now require that mt8195-power-controller is always
> a child of some parent device which will share its regmap/MMIO with it.
> 
> And what if in your next block there is no scpsys block and power
> controller is the scpsys alone? It's not possible with your bindings.

Do you mean a power controller node that looks like this?

scpsys: power-controller@...06000 {
	compatible = "mediatek,mt6797-scpsys";
	#power-domain-cells = <1>;

	// ...
};

> 
> Wouldn't it be better to assign some address space to the
> power-controller (now as an offset from scpsys)?

Is this mean adding an offset after the node name?

spm: power-controller@0 {
                     ^^

> 
> This is just wondering (Rockchip did the same...) and not a blocker as
> power-controller bindings are done.
> 
> Best regards,
> Krzysztof


Thanks,
TingHan