Subject: Re: [PATCH 05/40] arm64: dts: rockchip: Add frl-enable-gpios to rk3576-luckfox-core3576

From: Heiko Stuebner <[email-masked]>
Date: Fri, 17 Apr 2026 13:32:37 +0200

Hi Cristian,

the comments below apply sort of to all patches in that series.

Am Freitag, 17. April 2026, 11:24:39 Mitteleuropäische Sommerzeit schrieb Cristian Ciocaltea:
> The board exposes the GPIO4_C6 line to control the voltage bias on the
> HDMI data lines.  It must be asserted when operating in HDMI 2.1 FRL
> mode and deasserted for HDMI 1.4/2.0 TMDS mode.
> 
> Wire up the HDMI node to the GPIO line using the frl-enable-gpios
> property and drop the line from the vcc_5v0_hdmi regulator to allow
> adjusting the bias when transitioning between TMDS and FRL operating
> modes.
> 
> Signed-off-by: Cristian Ciocaltea <[email-masked]>
> ---
>  arch/arm64/boot/dts/rockchip/rk3576-luckfox-core3576.dtsi | 9 ++++-----
>  1 file changed, 4 insertions(+), 5 deletions(-)
> 
> diff --git a/arch/arm64/boot/dts/rockchip/rk3576-luckfox-core3576.dtsi b/arch/arm64/boot/dts/rockchip/rk3576-luckfox-core3576.dtsi
> index 749f0a54b478..93ae37699366 100644
> --- a/arch/arm64/boot/dts/rockchip/rk3576-luckfox-core3576.dtsi
> +++ b/arch/arm64/boot/dts/rockchip/rk3576-luckfox-core3576.dtsi
> @@ -140,10 +140,7 @@ regulator-state-mem {
>  
>  	vcc_5v0_hdmi: regulator-vcc-5v0-hdmi {
>  		compatible = "regulator-fixed";
> -		enable-active-high;
> -		gpios = <&gpio4 RK_PC6 GPIO_ACTIVE_HIGH>;
> -		pinctrl-names = "default";
> -		pinctrl-0 = <&hdmi_con_en>;
> +		regulator-always-on;
>  		regulator-min-microvolt = <5000000>;
>  		regulator-max-microvolt = <5000000>;
>  		regulator-name = "vcc_5v0_hdmi";

I think this regulator was sort of a complete hack, to set that
gpio to some sort of default state, by declaring it as hdmi-pwr-supply.

Only 2 rk3576 boards seem, to use that hack, so I think as that "regulator"
is completely functionless now, the whole thing could be removed?

> @@ -231,6 +228,8 @@ &gpu {
>  };
>  
>  &hdmi {
> +	pinctrl-0 = <&hdmi_txm0_pins &hdmi_tx_scl &hdmi_tx_sda &hdmi_frl_en>;
> +	frl-enable-gpios = <&gpio4 RK_PC6 GPIO_ACTIVE_LOW>;

this should be sorted the other way around I think.

Also please provide a pinctrl-names property too. If for whatever reason
the dw-hdmi aquires a 2nd pinctrl state in the future, this makes sure
board DTs are staying in the "old" compatible mode until they are adapted.

>  	status = "okay";
>  };
>  
> @@ -655,7 +654,7 @@ &pcie0 {
>  
>  &pinctrl {
>  	hdmi {
> -		hdmi_con_en: hdmi-con-en {
> +		hdmi_frl_en: hdmi-frl-en {

pinctrl names should ideally match the naming in schematics, for example
the "HDMI0_TX_ON_H" for jaguar and tiger. This makes it way easier to
go from DT to schematics and back.

>  			rockchip,pins = <4 RK_PC6 RK_FUNC_GPIO &pcfg_pull_none>;
>  		};
>  	};
> 
> 

Heiko