linux-kernel - Re: [PATCH v4 2/4] dt-bindings: arm: mediatek: Add new bindings of MediaTek frequency hopping

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Message-ID: <b5e4a2332942722f4138e5bf758f61e15dbad92e.camel@mediatek.com>
Date:   Fri, 21 Oct 2022 11:17:44 +0000
From:   Johnson Wang (王聖鑫) 
        <Johnson.Wang@...iatek.com>
To:     "sboyd@...nel.org" <sboyd@...nel.org>,
        "angelogioacchino.delregno@...labora.com" 
        <angelogioacchino.delregno@...labora.com>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "krzysztof.kozlowski+dt@...aro.org" 
        <krzysztof.kozlowski+dt@...aro.org>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-mediatek@...ts.infradead.org" 
        <linux-mediatek@...ts.infradead.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        Kuan-Hsin Lee (李冠新) 
        <Kuan-Hsin.Lee@...iatek.com>,
        Project_Global_Chrome_Upstream_Group 
        <Project_Global_Chrome_Upstream_Group@...iatek.com>,
        Yu-Chang Wang (王煜樟) 
        <Yu-Chang.Wang@...iatek.com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-clk@...r.kernel.org" <linux-clk@...r.kernel.org>,
        Edward-JW Yang (楊哲維) 
        <Edward-JW.Yang@...iatek.com>
Subject: Re: [PATCH v4 2/4] dt-bindings: arm: mediatek: Add new bindings of
 MediaTek frequency hopping

On Mon, 2022-10-17 at 12:04 -0700, Stephen Boyd wrote:
> Quoting Johnson Wang (王聖鑫) (2022-10-17 05:55:09)
> > On Fri, 2022-10-14 at 13:42 -0700, Stephen Boyd wrote:
> > > Quoting Johnson Wang (2022-10-13 04:23:34)
> > > > +  - |
> > > > +    #include <dt-bindings/clock/mt8186-clk.h>
> > > > +    fhctl: fhctl@...0ce00 {
> > > 
> > > Is it a clock-controller? 'fhctl' isn't a generic node name.
> > > 
> > 
> > This node is used for determining if PLLs adopt "hopping" method to
> > adjust their frequency.
> > It doesn't provide any clock but actually change the behavior of
> > some
> > PLLs with new .set_rate callback.
> > Do you think this node acts like one kind of clock-controller?
> 
> Why can't we add the reg and properties to the node that implements
> the
> PLL?

Hi Stephen,

Now we use standard clocks property to get clock indices from
apmixedsys node.

If we integrate the reg and properties into apmixedsys node, we have to
figure out another way to get indices... (I think one node shouldn't
take itself as input?)

There is an idea in my mind. Add these prperties into apmixedsys node.

	mediatek,hopping-clocks = <CLK_APMIXED_MAINPLL>,
			          <CLK_APMIXED_MSDCPLL>;
	mediatek,ssc-percent = <2 3>;


But I don't really know if this violates some rules.
Could you please give us some suggestion?
Thanks!

BRs,
Johnson Wang