linux-kernel - Re: [PATCH v3 03/11] arm64: dts: mt8195: Add SCP core 1 node

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Date:   Tue, 17 Jan 2023 08:19:35 +0000
From:   TingHan Shen (沈廷翰) 
        <TingHan.Shen@...iatek.com>
To:     "angelogioacchino.delregno@...labora.com" 
        <angelogioacchino.delregno@...labora.com>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        Tiffany Lin (林慧珊) 
        <tiffany.lin@...iatek.com>,
        "mchehab@...nel.org" <mchehab@...nel.org>,
        Yunfei Dong (董云飞) 
        <Yunfei.Dong@...iatek.com>,
        "krzysztof.kozlowski+dt@...aro.org" 
        <krzysztof.kozlowski+dt@...aro.org>,
        "matthias.bgg@...il.com" <matthias.bgg@...il.com>,
        "andersson@...nel.org" <andersson@...nel.org>,
        Andrew-CT Chen (陳智迪) 
        <Andrew-CT.Chen@...iatek.com>,
        "mathieu.poirier@...aro.org" <mathieu.poirier@...aro.org>
CC:     "linux-remoteproc@...r.kernel.org" <linux-remoteproc@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-mediatek@...ts.infradead.org" 
        <linux-mediatek@...ts.infradead.org>,
        "linux-media@...r.kernel.org" <linux-media@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>
Subject: Re: [PATCH v3 03/11] arm64: dts: mt8195: Add SCP core 1 node

On Tue, 2022-09-27 at 13:01 +0200, AngeloGioacchino Del Regno wrote:
> Il 27/09/22 04:55, Tinghan Shen ha scritto:
> > Add the 2nd core(core 1) of MT8195 dual-core SCP to devicetree file.
> > Reserve some SRAM spaces for the core 1 image.
> > 
> > Signed-off-by: Tinghan Shen <tinghan.shen@...iatek.com>
> > ---
> >   arch/arm64/boot/dts/mediatek/mt8195.dtsi | 14 +++++++++++++-
> >   1 file changed, 13 insertions(+), 1 deletion(-)
> > 
> > diff --git a/arch/arm64/boot/dts/mediatek/mt8195.dtsi b/arch/arm64/boot/dts/mediatek/mt8195.dtsi
> > index 905d1a90b406..48d457bd39b8 100644
> > --- a/arch/arm64/boot/dts/mediatek/mt8195.dtsi
> > +++ b/arch/arm64/boot/dts/mediatek/mt8195.dtsi
> > @@ -760,12 +760,24 @@
> >   
> >   		scp: scp@...00000 {
> >   			compatible = "mediatek,mt8195-scp";
> > -			reg = <0 0x10500000 0 0x100000>,
> > +			reg = <0 0x10500000 0 0xa0000>,
> >   			      <0 0x10720000 0 0xe0000>,
> >   			      <0 0x10700000 0 0x8000>;
> >   			reg-names = "sram", "cfg", "l1tcm";
> >   			interrupts = <GIC_SPI 462 IRQ_TYPE_LEVEL_HIGH 0>;
> >   			status = "disabled";
> > +
> > +			#address-cells = <1>;
> > +			#size-cells = <1>;
> > +			ranges = <0x105a0000 0 0x105a0000 0x20000>;
> > +
> > +			scp_c1: scp-c1@...a0000 {
> > +				compatible = "mediatek,mt8195-scp-core";
> > +				reg = <0x105a0000 0x20000>;
> > +				reg-names = "sram";
> > +				interrupts = <GIC_SPI 463 IRQ_TYPE_LEVEL_HIGH 0>;
> > +				status = "disabled";
> > +			};
> 
> I think that the best way of describing a dual-core SCP in devicetree would
> be either something like:
> 
> scp: scp@...00000 {
> 	compatible = "mediatek,mt8195-scp";
> 	reg = <0 0x10500000 0 0xa0000>, <0 0x105a0000 0 0x20000>,
> 	      <0 0x10720000 0 0xe0000>, <0 0x10700000 0 0x8000>;
> 	reg-names = "sram", "sram-c1", "cfg", "l1tcm";
> 	interrupts = <GIC_SPI 462 IRQ_TYPE_LEVEL_HIGH 0>,
> 		     <GIC_SPI 463 IRQ_TYPE_LEVEL_HIGH 0>;
> 	status = "disabled";
> };
> 
> ...but that may pose an issue when trying to assign different (or more instances
> of the same) subnode(s) to each core... for which, I'd be more for something like:
> 
> scp: scp@...00000 {
> 	compatible = "mediatek,mt8195-scp";
> 	reg = <0 0x10720000 0 0xe0000>, <0 0x10700000 0 0x8000>;
> 	reg-names = "cfg", "l1tcm";
> 	#address-cells = <1>;
> 	#size-cells = <1>;
> 	ranges = <0 0 0x10500000 0x100000>;
> 	status = "disabled";
> 
> 	scp_c0: scp-core@0 {
> 		compatible = "mediatek,mt8195-scp-core";
> 		reg = <0x0 0xa0000>;
> 		reg-names = "sram";
> 		interrupts = <GIC_SPI 462 IRQ_TYPE_LEVEL_HIGH 0>;
> 	};
> 
> 	scp_c1: scp-core@...00 {
> 		compatible = "mediatek,mt8195-scp-core";
> 		reg = <0xa0000 0x20000>;
> 		reg-names = "sram";
> 		interrupts = <GIC_SPI 463 IRQ_TYPE_LEVEL_HIGH 0>;
> 	};
> };
> 
> Regards,
> Angelo
> 
> 
Hi Angelo,

I'm thinking about identifying the cores by the order of the sub nodes, 
i.e. core 0 must be the first sub node and core 1 must be the second sub node, 
because the scp cores in the example have the same compatible name.

I'm hesitant to make the sub nodes appear in a certain order. Is it appropriate?
Or, would it be more readable to create a new core id property? Or utilizing 
different compatble strings for cores? I would appreciat it if you could share your opinion.


-- 
Best regards,
TingHan