linux-kernel - Re: [PATCH 3/3] arm64: dts: ti: k3-j7200-mcu-wakeup: Split fss node up

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Message-ID: <20230425122744.hkahpv6yvprd6qzy@creature>
Date:   Tue, 25 Apr 2023 07:27:44 -0500
From:   Nishanth Menon <nm@...com>
To:     Andrew Davis <afd@...com>
CC:     Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Vignesh Raghavendra <vigneshr@...com>,
        <linux-kernel@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        Tero Kristo <kristo@...nel.org>, <vaishnav.a@...com>,
        <u-kumar1@...com>
Subject: Re: [PATCH 3/3] arm64: dts: ti: k3-j7200-mcu-wakeup: Split fss node
 up

On 13:55-20230424, Andrew Davis wrote:
> On 4/24/23 12:36 PM, Nishanth Menon wrote:
> > fss node claims to be entirely a syscon node, but it is really two
> > parts of it - one a syscon that controls the hbmc mux and a simple bus
> > where ospi, hbmc peripherals are located. So model it accordingly by
> > splitting the node up and using ti,j721e-system-controller to describe
> > the syscon
> > 
> > Signed-off-by: Nishanth Menon <nm@...com>
> > ---
> >   .../boot/dts/ti/k3-j7200-mcu-wakeup.dtsi      | 21 +++++++++++++------
> >   1 file changed, 15 insertions(+), 6 deletions(-)
> > 
> > diff --git a/arch/arm64/boot/dts/ti/k3-j7200-mcu-wakeup.dtsi b/arch/arm64/boot/dts/ti/k3-j7200-mcu-wakeup.dtsi
> > index b58a31371bf3..7653cb191be1 100644
> > --- a/arch/arm64/boot/dts/ti/k3-j7200-mcu-wakeup.dtsi
> > +++ b/arch/arm64/boot/dts/ti/k3-j7200-mcu-wakeup.dtsi
> > @@ -338,18 +338,27 @@ mcu_spi2: spi@...20000 {
> >   		status = "disabled";
> >   	};
> > -	fss: syscon@...00000 {
> > -		compatible = "syscon", "simple-mfd";
> > +	hbmc_syscon: syscon@...00000 {
> > +		compatible = "ti,j721e-system-controller", "syscon", "simple-mfd";
> >   		reg = <0x00 0x47000000 0x00 0x100>;
> > -		#address-cells = <2>;
> > -		#size-cells = <2>;
> > -		ranges;
> > +		#address-cells = <1>;
> > +		#size-cells = <1>;
> > +		ranges = <0x00 0x00 0x47000000 0x100>;
> > -		hbmc_mux: hbmc-mux {
> > +		hbmc_mux: mux-controller@4 {
> >   			compatible = "mmio-mux";
> > +			reg = <0x4 0x2>;
> >   			#mux-control-cells = <1>;
> >   			mux-reg-masks = <0x4 0x2>; /* HBMC select */
> >   		};
> > +	};
> > +
> > +	fss: bus@...30000 {
> > +		compatible = "simple-bus";
> > +		reg = <0x0 0x47030000 0x0 0x100>;
> > +		#address-cells = <2>;
> > +		#size-cells = <2>;
> > +		ranges;
> >   		hbmc: hyperbus@...34000 {
> >   			compatible = "ti,am654-hbmc";
> 
> 
> I hope all the things you had to do here show you what I mean in my
> comments on [0] :)

yup.

> 
> I've posted a first step patch that allows "reg-mux" node to work with
> regular reg properties[1]. Which means this patch could have been just this:
> 
> --- a/arch/arm64/boot/dts/ti/k3-j7200-mcu-wakeup.dtsi
> +++ b/arch/arm64/boot/dts/ti/k3-j7200-mcu-wakeup.dtsi
> @@ -305,15 +305,16 @@ wkup_i2c0: i2c@...20000 {
>                 status = "disabled";
>         };
> -       fss: syscon@...00000 {
> -               compatible = "syscon", "simple-mfd";
> +       fss: bus@...00000 {
> +               compatible = "simple-bus";
>                 reg = <0x00 0x47000000 0x00 0x100>;
>                 #address-cells = <2>;
>                 #size-cells = <2>;
>                 ranges;
>                 hbmc_mux: hbmc-mux {
> -                       compatible = "mmio-mux";
> +                       compatible = "reg-mux";
> +                       reg = <0x00 0x47000004 0x00 0x2>;
>                         #mux-control-cells = <1>;
>                         mux-reg-masks = <0x4 0x2>; /* HBMC select */
>                 };
> 
> Andrew
> 
> [0] https://lore.kernel.org/all/76da0b98-3274-b047-db11-ecabc117ae11@ti.com/
> [1] https://lore.kernel.org/all/20230424184810.29453-1-afd@ti.com/

yes, this is a better approach. Lets see the conclusion of the
discussion.


-- 
Regards,
Nishanth Menon
Key (0xDDB5849D1736249D) / Fingerprint: F8A2 8693 54EB 8232 17A3  1A34 DDB5 849D 1736 249D