linux-kernel - Re: [PATCH 4/5] arm64: dts: imx8mp: convert 'aips5' to 'aipstz5'

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Message-ID: <Z8CWsI/DKZtDBkzE@lizhi-Precision-Tower-5810>
Date: Thu, 27 Feb 2025 11:45:36 -0500
From: Frank Li <Frank.li@....com>
To: Marc Kleine-Budde <mkl@...gutronix.de>
Cc: Mihalcea Laurentiu <laurentiumihalcea111@...il.com>,
	Daniel Baluta <daniel.baluta@....com>,
	Rob Herring <robh@...nel.org>, Conor Dooley <conor+dt@...nel.org>,
	devicetree@...r.kernel.org, Fabio Estevam <festevam@...il.com>,
	Sascha Hauer <s.hauer@...gutronix.de>, linux-kernel@...r.kernel.org,
	imx@...ts.linux.dev,
	Pengutronix Kernel Team <kernel@...gutronix.de>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Shawn Guo <shawnguo@...nel.org>,
	Shengjiu Wang <shengjiu.wang@....com>,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 4/5] arm64: dts: imx8mp: convert 'aips5' to 'aipstz5'

On Thu, Feb 27, 2025 at 11:57:54AM +0100, Marc Kleine-Budde wrote:
> On 25.02.2025 16:14:34, Mihalcea Laurentiu wrote:
> >
> > On 21.02.2025 21:56, Frank Li wrote:
> > > On Fri, Feb 21, 2025 at 02:19:08PM -0500, Laurentiu Mihalcea wrote:
> > >> From: Laurentiu Mihalcea <laurentiu.mihalcea@....com>
> > >>
> > >> AIPS5 is actually AIPSTZ5 as it offers some security-related
> > >> configurations. Since these configurations need to be applied before
> > >> accessing any of the peripherals on the bus, it's better to make AIPSTZ5
> > >> be their parent instead of keeping AIPS5 and adding a child node for
> > >> AIPSTZ5. Also, because of the security configurations, the address space
> > >> of the bus has to be changed to that of the configuration registers.
> > > The orginal 0x30c0_0000..0x31200000 include 0x30df0000, why not map only
> > > config address part in your drivers.
> > >
> > > Frank
> >
> >
> > Any concerns/anything wrong with current approach?
> >
> >
> > I find it a bit awkward to have the whole bus address space
> > in the DT given that we're only interested in using the access
> > controller register space.
> >
> >
> > I'm fine with the approach you suggested but I don't see a
> > reason for using it?
>
> Looking at the "AIPS5 Memory Map" (page 34/35 in i.MX 8M Plus
> Applications Processor Reference Manual, Rev. 3, 08/2024), the
> AIPS5_Configuration is part of the AIPS5 bus. IMHO the bus is something
> different than the bus configuration. Why not model it as part of the
> bus?
>
> > >> diff --git a/arch/arm64/boot/dts/freescale/imx8mp.dtsi b/arch/arm64/boot/dts/freescale/imx8mp.dtsi
> > >> index e0d3b8cba221..a1d9b834d2da 100644
> > >> --- a/arch/arm64/boot/dts/freescale/imx8mp.dtsi
> > >> +++ b/arch/arm64/boot/dts/freescale/imx8mp.dtsi
> > >> @@ -1399,11 +1399,13 @@ eqos: ethernet@...f0000 {
> > >>  			};
> > >>  		};
> > >>
> > >> -		aips5: bus@...00000 {
> > >> -			compatible = "fsl,aips-bus", "simple-bus";
> > >> -			reg = <0x30c00000 0x400000>;
> > >> +		aips5: bus@...f0000 {
>                        ^^^^^^^^^^^^
> > >> +			compatible = "fsl,imx8mp-aipstz", "simple-bus";
> > >> +			reg = <0x30df0000 0x10000>;
> > >> +			power-domains = <&pgc_audio>;
> > >>  			#address-cells = <1>;
> > >>  			#size-cells = <1>;
> > >> +			#access-controller-cells = <0>;
> > >>  			ranges;
> > >>
> > >>  			spba-bus@...00000 {
>                         ^^^^^^^^^^^^^^^^^
>
> This looks very strange: The aips5 bus starts at 0x30df0000 and has a
> child bus starting at 0x30c00000?

@30df0000 should match controller reg's address.

subnode address 0x30c00000,  should be descript in "ranges", which 1:1 map.

So it should be reasonable. another example:
i2c@...0 {

	device@1c <- which use difference address space.
}

The similar case also happen at pcie.

Frank

>
> regards,
> Marc
>
> --
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