linux-kernel - Re: [PATCH] arm64: dts: rockchip: fix nodename warning on wolfvision-pf5-display

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Message-ID: <3f93ecb0-a649-4492-8798-a00de26236c8@wolfvision.net>
Date: Tue, 23 Apr 2024 11:39:26 +0200
From: Michael Riesch <michael.riesch@...fvision.net>
To: Heiko Stuebner <heiko@...ech.de>
Cc: linux-arm-kernel@...ts.infradead.org, linux-rockchip@...ts.infradead.org,
 linux-kernel@...r.kernel.org, Arnd Bergmann <arnd@...nel.org>,
 devicetree <devicetree@...r.kernel.org>
Subject: Re: [PATCH] arm64: dts: rockchip: fix nodename warning on
 wolfvision-pf5-display

Hi Heiko,

First of all, thanks a lot for doing this!

On 4/23/24 10:29, Heiko Stuebner wrote:
> The dtbs check throws a warning about node naming with the recently
> added pf5-display-overlay:
> rockchip/rk3568-wolfvision-pf5-display.dtsi:113.6-121.3: Warning (graph_port): /fragment@..._overlay__: graph port node name should be 'port'
> 
> This comes from the overlay just referencing the vp2-port-node via
> its phandle and then adding an endpoint beneath it.
> 
> While this is possible something to handle inside the dtbs check,
> carrying around the warning is not pretty, so change the description
> to go around it.

What is the rationale behind that check? Describing a port in a SoC dtsi
or board dts and using the reference in an overlay is quite convenient
and above all concise.

Cc: device tree list
> Starting from the vop_out phandle and then referencing the port
> via its generic port@2 nodename will satisfy the port<->endpoint
> naming dependency while keeping the same structure once the overlay
> is applied.
> 
> Reported-by: Arnd Bergmann <arnd@...nel.org>
> Signed-off-by: Heiko Stuebner <heiko@...ech.de>
> ---
>  .../rockchip/rk3568-wolfvision-pf5-display.dtsi    | 14 ++++++++------
>  1 file changed, 8 insertions(+), 6 deletions(-)
> 
> diff --git a/arch/arm64/boot/dts/rockchip/rk3568-wolfvision-pf5-display.dtsi b/arch/arm64/boot/dts/rockchip/rk3568-wolfvision-pf5-display.dtsi
> index b22bb543ecbb..18c807c39e56 100644
> --- a/arch/arm64/boot/dts/rockchip/rk3568-wolfvision-pf5-display.dtsi
> +++ b/arch/arm64/boot/dts/rockchip/rk3568-wolfvision-pf5-display.dtsi
> @@ -110,12 +110,14 @@ &pwm10 {
>  	status = "okay";
>  };
>  
> -&vp2 {
> -	#address-cells = <1>;
> -	#size-cells = <0>;
> +&vop_out {
> +	port@2 {
> +		#address-cells = <1>;
> +		#size-cells = <0>;
>  
> -	vp2_out_rgb: endpoint@...KCHIP_VOP2_EP_RGB0 {
> -		reg = <ROCKCHIP_VOP2_EP_RGB0>;
> -		remote-endpoint = <&panel_in_vp2>;
> +		vp2_out_rgb: endpoint@...KCHIP_VOP2_EP_RGB0 {
> +			reg = <ROCKCHIP_VOP2_EP_RGB0>;
> +			remote-endpoint = <&panel_in_vp2>;
> +		};
>  	};
>  };

With this patch applied the DTC warning "Warning (graph_port):
/fragment@..._overlay__: graph port node name should be 'port'"
vanishes, but a different DTC warning "Warning (unit_address_vs_reg):
/fragment@..._overlay__/port@2: node has a unit name, but no reg or
ranges property" appears. Can you reproduce this?

I tried to fix that by adding the reg property, but then DTC complained
about "Warning (graph_port): /fragment@..._overlay__/ports/port@0: graph
node '#size-cells' is -1, must be 0"

Then, I added the #size-cells property to avoid this. However, DTC
complained about this property not being necessary as there is only one
port. I stopped at this point.

I would say the real question is how this hardware should look like in
the device tree (overlay). Then, the compiler and/or build scripts can
be adjusted to tolerate this.

Thanks and best regards,
Michael