RE: (EXT) [PATCH v2 6/7] arm64: dts: imx8mp-evk: Add PCIe support

[Hongxing Zhu <hongxing.zhu@nxp.com>]

> -----Original Message-----
> From: Alexander Stein <alexander.stein@ew.tq-group.com>
> Sent: 2022年3月24日 18:05
> To: p.zabel@pengutronix.de; l.stach@pengutronix.de; bhelgaas@google.com;
> lorenzo.pieralisi@arm.com; robh@kernel.org; shawnguo@kernel.org;
> vkoul@kernel.org; Hongxing Zhu <hongxing.zhu@nxp.com>
> Cc: linux-phy@lists.infradead.org; devicetree@vger.kernel.org;
> linux-pci@vger.kernel.org; linux-arm-kernel@lists.infradead.org;
> linux-kernel@vger.kernel.org; kernel@pengutronix.de; dl-linux-imx
> <linux-imx@nxp.com>; Hongxing Zhu <hongxing.zhu@nxp.com>
> Subject: Re: (EXT) [PATCH v2 6/7] arm64: dts: imx8mp-evk: Add PCIe support
> 
> Hello Richard,
> 
> thanks for providing PCIe support for iMX8MP.
> 
> Am Montag, 7. März 2022, 10:07:33 CET schrieb Richard Zhu:
> > Add PCIe support on i.MX8MP EVK board.
> >
> > Signed-off-by: Richard Zhu <hongxing.zhu@nxp.com>
> > ---
> >  arch/arm64/boot/dts/freescale/imx8mp-evk.dts | 55
> > ++++++++++++++++++++
> >  1 file changed, 55 insertions(+)
> >
> > diff --git a/arch/arm64/boot/dts/freescale/imx8mp-evk.dts
> > b/arch/arm64/boot/dts/freescale/imx8mp-evk.dts index
> > 2eb943210678..ed77455a3f73 100644
> > --- a/arch/arm64/boot/dts/freescale/imx8mp-evk.dts
> > +++ b/arch/arm64/boot/dts/freescale/imx8mp-evk.dts
> > @@ -5,6 +5,7 @@
> >
> >  /dts-v1/;
> >
> > +#include <dt-bindings/phy/phy-imx8-pcie.h>
> >  #include "imx8mp.dtsi"
> >
> >  / {
> > @@ -33,6 +34,12 @@ memory@40000000 {
> >  		      <0x1 0x00000000 0 0xc0000000>;
> >  	};
> >
> > +	pcie0_refclk: pcie0-refclk {
> > +		compatible = "fixed-clock";
> > +			#clock-cells = <0>;
> > +			clock-frequency = <100000000>;
> > +	};
> > +
> >  	reg_can1_stby: regulator-can1-stby {
> >  		compatible = "regulator-fixed";
> >  		regulator-name = "can1-stby";
> > @@ -55,6 +62,17 @@ reg_can2_stby: regulator-can2-stby {
> >  		enable-active-high;
> >  	};
> >
> > +	reg_pcie0: regulator-pcie {
> > +		compatible = "regulator-fixed";
> > +		pinctrl-names = "default";
> > +		pinctrl-0 = <&pinctrl_pcie0_reg>;
> > +		regulator-name = "MPCIE_3V3";
> > +		regulator-min-microvolt = <3300000>;
> > +		regulator-max-microvolt = <3300000>;
> > +		gpio = <&gpio2 6 GPIO_ACTIVE_HIGH>;
> > +		enable-active-high;
> > +	};
> > +
> >  	reg_usdhc2_vmmc: regulator-usdhc2 {
> >  		compatible = "regulator-fixed";
> >  		pinctrl-names = "default";
> > @@ -297,6 +315,30 @@ pca6416: gpio@20 {
> >  	};
> >  };
> >
> > +&pcie_phy {
> > +	fsl,refclk-pad-mode = <IMX8_PCIE_REFCLK_PAD_INPUT>;
> > +	clocks = <&pcie0_refclk>;
> > +	clock-names = "ref";
> > +	status = "okay";
> > +};
> > +
> > +&pcie{
> > +	pinctrl-names = "default";
> > +	pinctrl-0 = <&pinctrl_pcie0>;
> > +	reset-gpio = <&gpio2 7 GPIO_ACTIVE_LOW>;
> > +	clocks = <&clk IMX8MP_CLK_HSIO_ROOT>,
> > +		 <&clk IMX8MP_CLK_PCIE_ROOT>,
> > +		 <&clk IMX8MP_CLK_HSIO_AXI>;
> > +	clock-names = "pcie", "pcie_aux", "pcie_bus";
> 
> This causes the following warnings in dtbs_check (paths stripped):
> imx8mp-evk.dtb: pcie@33800000: clock-names:1: 'pcie_bus' was expected
>         From schema:
> Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.yaml
> imx8mp-evk.dtb: pcie@33800000: clock-names:2: 'pcie_phy' was expected
>         From schema:
> Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.yaml
> 
> The bindings want 4 clocks for imx8mq (and imx8mp which seems similar):
> * pcie
> * pcie_bus
> * pcie_phy
> * pcie_aux
> 
> Ignoring the order there is no pcie_phy clock anymore, it was removed in
> commit 1840518ae7de ("clk: imx8mp: Remove the none exist pcie clocks"). I
> was wondering why, because the PCIE_PHY_CLK_ROOT at register 0xa380
> inside CCM is listed in RM.
> So there is a clock missing for 'pcie_phy' or the binding needs some update for
> imx8mp, no?
Hi Alexander:
Thanks for your comments.
I had confirmed with design team, the PCIE_PHY_CLK_ROOT at register 0xa380 is
 not used anymore on i.MX8MP PCIe. So I used to issue one patch to remove the
useless code from clock driver.
About the dt-binding of the i.MX8MP clocks, I would update the yaml later.
BTW, i.MX8MP PCIe is similar to the i.MX8MM PCIe's.
It's better to make reference to the i.MX8MM PCIe clocks definitions.

Best Regards
Richard Zhu

> 
> Regards,
> Alexander
> 
> > +	assigned-clocks = <&clk IMX8MP_CLK_HSIO_AXI>,
> > +			  <&clk IMX8MP_CLK_PCIE_AUX>;
> > +	assigned-clock-rates = <500000000>, <10000000>;
> > +	assigned-clock-parents = <&clk IMX8MP_SYS_PLL2_500M>,
> > +				 <&clk IMX8MP_SYS_PLL2_50M>;
> > +	vpcie-supply = <&reg_pcie0>;
> > +	status = "okay";
> > +};
> > +
> >  &snvs_pwrkey {
> >  	status = "okay";
> >  };
> > @@ -442,6 +484,19 @@ MX8MP_IOMUXC_I2C3_SDA__I2C3_SDA
> 	0x400001c3
> >
> >  		>;
> >
> >  	};
> >
> > +	pinctrl_pcie0: pcie0grp {
> > +		fsl,pins = <
> > +			MX8MP_IOMUXC_I2C4_SCL__PCIE_CLKREQ_B
> 0x61 /* open drain, pull up */
> > +			MX8MP_IOMUXC_SD1_DATA5__GPIO2_IO07
> 0x41
> > +		>;
> > +	};
> > +
> > +	pinctrl_pcie0_reg: pcie0reggrp {
> > +		fsl,pins = <
> > +			MX8MP_IOMUXC_SD1_DATA4__GPIO2_IO06
> 0x41
> > +		>;
> > +	};
> > +
> >  	pinctrl_pmic: pmicgrp {
> >  		fsl,pins = <
> >  			MX8MP_IOMUXC_GPIO1_IO03__GPIO1_IO03
> 0x000001c0
> 
> 
>