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[75.72.117.212]) by smtp.gmail.com with ESMTPSA id ca18e2360f4ac-92d06cc3b9esm184392139f.12.2025.09.30.19.40.13 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 30 Sep 2025 19:40:15 -0700 (PDT) Message-ID: <365ade7c-bb2c-42ff-a2e7-9a291b1faab7@riscstar.com> Date: Tue, 30 Sep 2025 21:40:12 -0500 Precedence: bulk X-Mailing-List: linux-pci@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 3/6] dt-bindings: phy: spacemit: introduce PCIe root complex To: Manivannan Sadhasivam Cc: robh@kernel.org, krzk+dt@kernel.org, conor+dt@kernel.org, lpieralisi@kernel.org, kwilczynski@kernel.org, bhelgaas@google.com, vkoul@kernel.org, kishon@kernel.org, dlan@gentoo.org, paul.walmsley@sifive.com, palmer@dabbelt.com, aou@eecs.berkeley.edu, alex@ghiti.fr, p.zabel@pengutronix.de, tglx@linutronix.de, johan+linaro@kernel.org, thippeswamy.havalige@amd.com, namcao@linutronix.de, mayank.rana@oss.qualcomm.com, shradha.t@samsung.com, inochiama@gmail.com, quic_schintav@quicinc.com, fan.ni@samsung.com, devicetree@vger.kernel.org, linux-phy@lists.infradead.org, linux-pci@vger.kernel.org, spacemit@lists.linux.dev, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org References: <20250813184701.2444372-1-elder@riscstar.com> <20250813184701.2444372-4-elder@riscstar.com> <804ea57f-699f-41cc-a27c-844f107e627f@riscstar.com> Content-Language: en-US From: Alex Elder In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 9/20/25 12:55 AM, Manivannan Sadhasivam wrote: > On Fri, Sep 19, 2025 at 03:14:05PM -0500, Alex Elder wrote: >> On 9/15/25 3:14 AM, Manivannan Sadhasivam wrote: >>> On Wed, Aug 13, 2025 at 01:46:57PM GMT, Alex Elder wrote: >>> >>> Subject should have 'pci' prefix, not 'phy'. >> >> OK I'll update that in the next version. I have a new version of this code ready, but I'll delay sending it until the end of the merge window. >>>> Add the Device Tree binding for the PCIe root complex found on the >>>> SpacemiT K1 SoC. This device is derived from the Synopsys Designware >>>> PCIe IP. It supports up to three PCIe ports operating at PCIe gen 2 >>>> link speeds (5 GT/sec). One of the ports uses a combo PHY, which is >>>> typically used to support a USB 3 port. >>>> >>>> Signed-off-by: Alex Elder >>>> --- >>>> .../bindings/pci/spacemit,k1-pcie-rc.yaml | 141 ++++++++++++++++++ >>>> 1 file changed, 141 insertions(+) >>>> create mode 100644 Documentation/devicetree/bindings/pci/spacemit,k1-pcie-rc.yaml >>>> >>>> diff --git a/Documentation/devicetree/bindings/pci/spacemit,k1-pcie-rc.yaml b/Documentation/devicetree/bindings/pci/spacemit,k1-pcie-rc.yaml >>>> new file mode 100644 >>>> index 0000000000000..6bcca2f91a6fd >>>> --- /dev/null >>>> +++ b/Documentation/devicetree/bindings/pci/spacemit,k1-pcie-rc.yaml >>>> @@ -0,0 +1,141 @@ . . . >>>> + interrupts-extended: >>>> + maxItems: 1 >>> >>> What is the purpose of this property? Is it for MSI or INTx? >> >> It is for MSIs, which are translated into this interrupt. >> I'll add a short description indicating this. >> >> Is there a better way to represent this? >> > > For external MSI controllers, it is recommended to use 'msi-map' property as the > client often need to pass RID, RID length and other sideband data to the MSI > controller. This implementation is using the DWC built-in MSI controller, not an external controller. It implements 256 MSIs, and they're handled by dw_handle_msi_irq(). The interrupt will be given name "msi" in the next version and I hope that at least helps clarify things. > >>>> + >>>> + spacemit,syscon-pmu: >>>> + description: >>>> + PHandle that refers to the APMU system controller, whose >>>> + regmap is used in managing resets and link state. >>>> + $ref: /schemas/types.yaml#/definitions/phandle >>>> + >>>> + device_type: >>>> + const: pci >>>> + >>>> + max-link-speed: >>>> + const: 2 >>> >>> Why do you need to limit it to 5 GT/s always? >> >> It's what the hardware overview says is the speed >> of the ports. >> PCIE PortA Gen2x1 >> PCIE PortB Gen2x2 >> PCIE PortC Gen2x2 >> >> But I think what you're asking might be "why do you >> need to specify in DT that the link speed is limited". >> And in that case, I realize now that it is not needed. >> I will specify dw_pcie->max_link_speed to 2 before >> calling dw_pcie_host_init(). >> > > You only need to specify this property if you want to limit the link speed to a > certain data rate by the controller driver than what is supported by the > hardware. Yes, this makes sense. > Looks like your hardware supports 5 GT/s by default for all ports. So you can > omit this property and also no need to set 'dw_pcie->max_link_speed'. In the > absence of this property, 'dw_pcie->max_link_speed' will be populated with the > hardware default value, which will be 2 in your case. You are correct, and I verified this. I won't specify the link speed "manually," and the hardware default (which is 2) will be used. >> If that's not what you meant, please let me know. >> >>>> + num-viewport: >>>> + const: 8 >>>> + >>>> +required: >>>> + - compatible >>>> + - reg >>>> + - clocks >>>> + - clock-names >>>> + - resets >>>> + - reset-names >>>> + - spacemit,syscon-pmu >>>> + - "#address-cells" >>>> + - "#size-cells" >>>> + - device_type >>>> + - max-link-speed >>> >>> Same comment as above. >>> >>>> + - bus-range >>>> + - num-viewport >>>> + >>>> +additionalProperties: false >>>> + >>>> +examples: >>>> + - | >>>> + #include >>>> + pcie0: pcie@ca000000 { >>>> + compatible = "spacemit,k1-pcie-rc"; >>>> + reg = <0x0 0xca000000 0x0 0x00001000>, >>>> + <0x0 0xca300000 0x0 0x0001ff24>, >>>> + <0x0 0x8f000000 0x0 0x00002000>, >>>> + <0x0 0xc0b20000 0x0 0x00001000>; >>>> + reg-names = "dbi", >>>> + "atu", >>>> + "config", >>>> + "link"; >>>> + >>>> + ranges = <0x01000000 0x8f002000 0x0 0x8f002000 0x0 0x100000>, >>> >>> I/O port CPU address starts from 0. >> >> First, I'm not sure what this comment means. >> > > Sorry, I meant to say 'PCI address' not 'CPU address'. The second element in > your 'ranges' example corresponds to the PCI start address of the I/O port and > it should always start from 0. Also, the encoding for both tuples are wrong. It > should be: > > ranges = <0x01000000 0x0 0x00000000 0x8f002000 0x0 0x100000>, > <0x02000000 0x0 0x80000000 0x80000000 0x0 0x0f000000>; Simply switching to what you show works just fine. PCI addresses show up being zero-based, as they should be. What I don't fully understand is why it worked before. Maybe because this is simply defining bounds in the mapping? In any case, I am using ranges properties like what you show. Thanks Mani. -Alex > - Mani