linux-kernel - Re: [PATCH 1/2] dt-bindings: PCI: meson: add DT bindings for Amlogic Meson PCIe controller

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Message-ID: <fd6b76f0c6f5b4dfd1527440b0f6275417e434c1.camel@baylibre.com>
Date:   Tue, 14 Aug 2018 12:41:26 +0200
From:   Jerome Brunet <jbrunet@...libre.com>
To:     Hanjie Lin <hanjie.lin@...ogic.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>
Cc:     Yue Wang <yue.wang@...ogic.com>,
        Kevin Hilman <khilman@...libre.com>,
        Rob Herring <robh@...nel.org>, linux-kernel@...r.kernel.org,
        linux-pci@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-amlogic@...ts.infradead.org, devicetree@...r.kernel.org
Subject: Re: [PATCH 1/2] dt-bindings: PCI: meson: add DT bindings for
 Amlogic Meson PCIe controller

On Tue, 2018-08-14 at 02:18 -0400, Hanjie Lin wrote:
> From: Yue Wang <yue.wang@...ogic.com>
> 
> The Amlogic Meson PCIe host controller is based on the Synopsys DesignWare
> PCI core. This patch adds documentation for the DT bindings in Meson PCIe
> controller.
> 
> Signed-off-by: Yue Wang <hanjie.lin@...ogic.com>
> Signed-off-by: Hanjie Lin <hanjie.lin@...ogic.com>
> ---
>  .../devicetree/bindings/pci/amlogic,meson-pcie.txt | 57 ++++++++++++++++++++++
>  1 file changed, 57 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/pci/amlogic,meson-pcie.txt
> 
> diff --git a/Documentation/devicetree/bindings/pci/amlogic,meson-pcie.txt b/Documentation/devicetree/bindings/pci/amlogic,meson-pcie.txt
> new file mode 100644
> index 0000000..48233e4
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/pci/amlogic,meson-pcie.txt
> @@ -0,0 +1,57 @@
> +Amlogic Meson AXG DWC PCIE SoC controller
> +
> +Amlogic Meson PCIe host controller is based on the Synopsys DesignWare PCI core.
> +It shares common functions with the PCIe DesignWare core driver and
> +inherits common properties defined in
> +Documentation/devicetree/bindings/pci/designware-pci.txt.
> +
> +Additional properties are described here:
> +
> +Required properties:
> +- compatible:
> +	should contain "amlogic,axg-pcie" to identify the core.
> +- reg:
> +	Should contain the configuration address space.
> +- reg-names: Must be
> +	- "elbi"	External local bus interface registers
> +	- "cfg"		Meson specific registers
> +	- "config"	PCIe configuration space
> +- clocks: Must contain an entry for each entry in clock-names.
> +- clock-names: Must include the following entries:
> +	- "pcie"
> +	- "pcie_bus"
> +	- "pcie_general"
> +	- "pcie_mipi_en"

Could you briefly describe what each clock is needed for ?

> +
> +Example configuration:
> +
> +	pcie: pcie@...ff000 {
> +			compatible = "amlogic,axg-pcie", "snps,dw-pcie";
> +			reg = <0x0 0xf9800000 0x0 0x400000
> +					0x0 0xff646000 0x0 0x2000
> +					0x0 0xf9f00000 0x0 0x100000>;
> +			reg-names = "elbi", "cfg", "config";
> +			reset-gpio = <&gpio GPIOX_19 GPIO_ACTIVE_HIGH>;
> +			interrupts = <0 177 IRQ_TYPE_EDGE_RISING>;

replace 0 with GIC_SPI please

> +			#interrupt-cells = <1>;
> +			interrupt-map-mask = <0 0 0 0>;
> +			interrupt-map = <0 0 0 0 &gic GIC_SPI 179 IRQ_TYPE_EDGE_RISING>;
> +			bus-range = <0x0 0xff>;
> +			#address-cells = <3>;
> +			#size-cells = <2>;
> +			device_type = "pci";
> +			phys = <&pcie_phy>;
> +			ranges = <0x82000000 0 0 0x0 0xf9c00000 0 0x00300000>;
> +			num-lanes = <1>;
> +			pcie-num = <1>;
> +
> +			clocks = <&clkc CLKID_USB
> +					&clkc CLKID_MIPI_ENABLE
> +					&clkc CLKID_PCIE_A
> +					&clkc CLKID_PCIE_CML_EN0>;
> +			clock-names = "pcie_general",
> +					"pcie_refpll",
> +					"pcie_mipi_en",
> +					"pcie",
> +					"port";

Several things are disturbing above:
* pcie_general is provided by the USB clock gate ???
* pcie_refpll: I suppose this is a copy/paste error, not used in your driver
(and shouldn't be need BTW)

suggested names:
* pcie_general -> general
* pcie_mipi_en -> mipi
* pcie -> pclk
* port (OK)

> +	};