Re: [PATCH v2 2/4] arm64: dts: rockchip: use gated-fixed-clock for pcie-refclk on rk3588-tiger

Shawn Lin
2026-02-11T14:24:59Z

在 2026/02/10 星期二 16:03, Heiko Stuebner 写道:
> From: Heiko Stuebner <heiko.stuebner@cherry.de>
>
> Using a combination of fixed clock and gpio-gate clock works but does
> not describe the actual hardware. Use the gated-fixed-clock binding
> to describe this in a nicer way.
>
> Signed-off-by: Heiko Stuebner <heiko.stuebner@cherry.de>
> ---
> .../arm64/boot/dts/rockchip/rk3588-tiger.dtsi | 19 +++++--------------
> 1 file changed, 5 insertions(+), 14 deletions(-)
>
> diff --git a/arch/arm64/boot/dts/rockchip/rk3588-tiger.dtsi b/arch/arm64/boot/dts/rockchip/rk3588-tiger.dtsi
> index 27269b7b08aa..b4b8f305935f 100644
> --- a/arch/arm64/boot/dts/rockchip/rk3588-tiger.dtsi
> +++ b/arch/arm64/boot/dts/rockchip/rk3588-tiger.dtsi
> @@ -47,23 +47,14 @@ led-1 {
> };
> };
>
> - /*
> - * 100MHz reference clock for PCIe peripherals from PI6C557-05BLE
> - * clock generator.
> - * The clock output is gated via the OE pin on the clock generator.
> - * This is modeled as a fixed-clock plus a gpio-gate-clock.
> - */
> - pcie_refclk_gen: pcie-refclk-gen-clock {
> - compatible = "fixed-clock";
> + /* 100MHz PCIe reference clock from PI6C557-05BLE */
> + pcie_refclk: pcie-clock-generator {
> + compatible = "gated-fixed-clock";
> #clock-cells = <0>;
> clock-frequency = <100000000>;
> - };
> -
> - pcie_refclk: pcie-refclk-clock {
> - compatible = "gpio-gate-clock";
> - clocks = <&pcie_refclk_gen>;
> - #clock-cells = <0>;
> + clock-output-names = "pcie-refclk-clock";
> enable-gpios = <&gpio4 RK_PB4 GPIO_ACTIVE_HIGH>; /* PCIE30X4_CLKREQN_M1_L */

The change itself looks fine , so
Reviewed-by: Shawn Lin <shawn.lin@rock-chips.com>

However, if it's designed as active high, I would say Tiger is against
the the PCIe spec about how L1 substate work. Perhaps you could check
PCIe spec v7.0, Figure 5-16 Example: L1.2 Waveforms Illustrating
Upstream Port Initiated Exit.. When in L1.2, clkreq# should be released
by both ends, and the pull-up register by whatevery way will make it
into high, and thus refclk is gated automatically.

> + vdd-supply = <&vcca_3v3_s0>;
> };
>
> vcc_1v1_nldo_s3: regulator-vcc-1v1-nldo-s3 {