linux-kernel - Re: [PATCH v2] arm64: dts: rockchip: Add missing pinctrl for PCIe30x4 node

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Message-ID: <a8c1f49e-bf25-4fd3-a16f-13088f75767f@kwiboo.se>
Date: Thu, 11 Jul 2024 10:43:10 +0200
From: Jonas Karlman <jonas@...boo.se>
To: Anand Moon <linux.amoon@...il.com>, Heiko Stuebner <heiko@...ech.de>
Cc: Rob Herring <robh@...nel.org>, Krzysztof Kozlowski
 <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>,
 devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
 linux-rockchip@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] arm64: dts: rockchip: Add missing pinctrl for PCIe30x4
 node

Hi Anand,

On 2024-07-11 08:09, Anand Moon wrote:
> Add missing pinctrl settings for PCIe 3.0 x4 clock request and wake
> signals.Each component of PCIe communication have the following control
> signals: PERST, WAKE, CLKREQ, and REFCLK. These signals work to generate
> high-speed signals and communicate with other PCIe devices.
> Used by root complex to endpoint depending on the power state.
> 
> PERST is referred to as a fundamental reset. PERST should be held low
> until all the power rails in the system and the reference clock are stable.
> A transition from low to high in this signal usually indicates the
> beginning of link initialization.
> 
> WAKE signal is an active-low signal that is used to return the PCIe
> interface to an active state when in a low-power state.
> 
> CLKREQ signal is also an active-low signal and is used to request the
> reference clock.
> 
> Signed-off-by: Anand Moon <linux.amoon@...il.com>
> ---
> V2: Update the commit messge to describe the changs.
>     use pinctl group as its pre define in pinctl dtsi
> ---
>  arch/arm64/boot/dts/rockchip/rk3588-rock-5b.dts | 6 +-----
>  1 file changed, 1 insertion(+), 5 deletions(-)
> 
> diff --git a/arch/arm64/boot/dts/rockchip/rk3588-rock-5b.dts b/arch/arm64/boot/dts/rockchip/rk3588-rock-5b.dts
> index 2e7512676b7e..ab3a20986c6a 100644
> --- a/arch/arm64/boot/dts/rockchip/rk3588-rock-5b.dts
> +++ b/arch/arm64/boot/dts/rockchip/rk3588-rock-5b.dts
> @@ -301,7 +301,7 @@ &pcie30phy {
>  
>  &pcie3x4 {
>  	pinctrl-names = "default";
> -	pinctrl-0 = <&pcie3_rst>;
> +	pinctrl-0 = <&pcie30x4m1_pins>;

Use of the existing pcie30x4m1_pins group may not be fully accurate for
the PERST pin. The use of reset-gpios indicate that the PERST pin is
used with GPIO function and the driver will implicitly change the
function from perstn_m1 to GPIO. So this may not be best representation
of the hw, hence my initial suggestion, something like:

	pcie30x4_pins: pcie30x4-pins {
		rockchip,pins =
			<4 RK_PB4 4 &pcfg_pull_none>,
			<4 RK_PB6 RK_FUNC_GPIO &pcfg_pull_none>,
			<4 RK_PB5 4 &pcfg_pull_none>;
	};

Similar change should probably also be done for pcie2x1l0 and pcie2x1l2,
not just pcie3x4.

Regards,
Jonas

>  	reset-gpios = <&gpio4 RK_PB6 GPIO_ACTIVE_HIGH>;
>  	vpcie3v3-supply = <&vcc3v3_pcie30>;
>  	status = "okay";
> @@ -341,10 +341,6 @@ pcie2_2_rst: pcie2-2-rst {
>  	};
>  
>  	pcie3 {
> -		pcie3_rst: pcie3-rst {
> -			rockchip,pins = <4 RK_PB6 RK_FUNC_GPIO &pcfg_pull_none>;
> -		};
> -
>  		pcie3_vcc3v3_en: pcie3-vcc3v3-en {
>  			rockchip,pins = <1 RK_PA4 RK_FUNC_GPIO &pcfg_pull_none>;
>  		};
> 
> base-commit: 34afb82a3c67f869267a26f593b6f8fc6bf35905