linux-kernel - Re: [PATCH v6 5/6] arm64: dts: qcom: ipq5018: Add PCIe related nodes

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Message-ID: <5b7bb606-c763-4243-808e-5a1dd2f5b17e@oss.qualcomm.com>
Date: Mon, 24 Mar 2025 20:40:16 +0100
From: Konrad Dybcio <konrad.dybcio@....qualcomm.com>
To: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>,
        Praveenkumar I <quic_ipkumar@...cinc.com>
Cc: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
        george.moussalem@...look.com, Vinod Koul <vkoul@...nel.org>,
        Kishon Vijay Abraham I <kishon@...nel.org>,
        Rob Herring <robh@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Conor Dooley
 <conor+dt@...nel.org>,
        Nitheesh Sekar <quic_nsekar@...cinc.com>,
        Varadarajan Narayanan <quic_varada@...cinc.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Lorenzo Pieralisi <lpieralisi@...nel.org>,
        Krzysztof Wilczyński <kw@...ux.com>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konradybcio@...nel.org>, linux-arm-msm@...r.kernel.org,
        linux-phy@...ts.infradead.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org,
        20250317100029.881286-2-quic_varada@...cinc.com,
        Sricharan R <quic_srichara@...cinc.com>
Subject: Re: [PATCH v6 5/6] arm64: dts: qcom: ipq5018: Add PCIe related nodes

On 3/24/25 12:36 PM, Dmitry Baryshkov wrote:
> On Mon, Mar 24, 2025 at 04:48:34PM +0530, Praveenkumar I wrote:
>>
>>
>> On 3/24/2025 1:26 PM, Manivannan Sadhasivam wrote:
>>> On Fri, Mar 21, 2025 at 04:14:43PM +0400, George Moussalem via B4 Relay wrote:
>>>> From: Nitheesh Sekar<quic_nsekar@...cinc.com>
>>>>
>>>> Add phy and controller nodes for a 2-lane Gen2 and
>>> Controller is Gen 3 capable but you are limiting it to Gen 2.
>>>
>>>> a 1-lane Gen2 PCIe bus. IPQ5018 has 8 MSI SPI interrupts and
>>>> one global interrupt.
>>>>
>>>> Signed-off-by: Nitheesh Sekar<quic_nsekar@...cinc.com>
>>>> Signed-off-by: Sricharan R<quic_srichara@...cinc.com>
>>>> Signed-off-by: George Moussalem<george.moussalem@...look.com>
>>> One comment below. With that addressed,
>>>
>>> Reviewed-by: Manivannan Sadhasivam<manivannan.sadhasivam@...aro.org>
>>>
>>>> ---
>>>>   arch/arm64/boot/dts/qcom/ipq5018.dtsi | 234 +++++++++++++++++++++++++++++++++-
>>>>   1 file changed, 232 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/arch/arm64/boot/dts/qcom/ipq5018.dtsi b/arch/arm64/boot/dts/qcom/ipq5018.dtsi
>>>> index 8914f2ef0bc4..d08034b57e80 100644
>>>> --- a/arch/arm64/boot/dts/qcom/ipq5018.dtsi
>>>> +++ b/arch/arm64/boot/dts/qcom/ipq5018.dtsi
>>>> @@ -147,6 +147,40 @@ usbphy0: phy@...00 {
>>>>   			status = "disabled";
>>>>   		};
>>>> +		pcie1_phy: phy@...00{
>>>> +			compatible = "qcom,ipq5018-uniphy-pcie-phy";
>>>> +			reg = <0x0007e000 0x800>;
>>>> +
>>>> +			clocks = <&gcc GCC_PCIE1_PIPE_CLK>;
>>>> +
>>>> +			resets = <&gcc GCC_PCIE1_PHY_BCR>,
>>>> +				 <&gcc GCC_PCIE1PHY_PHY_BCR>;
>>>> +
>>>> +			#clock-cells = <0>;
>>>> +			#phy-cells = <0>;
>>>> +
>>>> +			num-lanes = <1>;
>>>> +
>>>> +			status = "disabled";
>>>> +		};
>>>> +
>>>> +		pcie0_phy: phy@...00{
>>>> +			compatible = "qcom,ipq5018-uniphy-pcie-phy";
>>>> +			reg = <0x00086000 0x800>;
>>>> +
>>>> +			clocks = <&gcc GCC_PCIE0_PIPE_CLK>;
>>>> +
>>>> +			resets = <&gcc GCC_PCIE0_PHY_BCR>,
>>>> +				 <&gcc GCC_PCIE0PHY_PHY_BCR>;
>>>> +
>>>> +			#clock-cells = <0>;
>>>> +			#phy-cells = <0>;
>>>> +
>>>> +			num-lanes = <2>;
>>>> +
>>>> +			status = "disabled";
>>>> +		};
>>>> +
>>>>   		tlmm: pinctrl@...0000 {
>>>>   			compatible = "qcom,ipq5018-tlmm";
>>>>   			reg = <0x01000000 0x300000>;
>>>> @@ -170,8 +204,8 @@ gcc: clock-controller@...0000 {
>>>>   			reg = <0x01800000 0x80000>;
>>>>   			clocks = <&xo_board_clk>,
>>>>   				 <&sleep_clk>,
>>>> -				 <0>,
>>>> -				 <0>,
>>>> +				 <&pcie0_phy>,
>>>> +				 <&pcie1_phy>,
>>>>   				 <0>,
>>>>   				 <0>,
>>>>   				 <0>,
>>>> @@ -387,6 +421,202 @@ frame@...8000 {
>>>>   				status = "disabled";
>>>>   			};
>>>>   		};
>>>> +
>>>> +		pcie1: pcie@...00000 {
>>>> +			compatible = "qcom,pcie-ipq5018";
>>>> +			reg = <0x80000000 0xf1d>,
>>>> +			      <0x80000f20 0xa8>,
>>>> +			      <0x80001000 0x1000>,
>>>> +			      <0x00078000 0x3000>,
>>>> +			      <0x80100000 0x1000>,
>>>> +			      <0x0007b000 0x1000>;
>>>> +			reg-names = "dbi",
>>>> +				    "elbi",
>>>> +				    "atu",
>>>> +				    "parf",
>>>> +				    "config",
>>>> +				    "mhi";
>>>> +			device_type = "pci";
>>>> +			linux,pci-domain = <0>;
>>>> +			bus-range = <0x00 0xff>;
>>>> +			num-lanes = <1>;
>>>> +			max-link-speed = <2>;
>>> This still needs some justification. If Qcom folks didn't reply, atleast move
>>> this to board dts with a comment saying that the link is not coming up with
>>> Gen3.
>>>
>>> - Mani
>> The IPQ5018 PCIe controller can support Gen3, but the PCIe phy is limited
>> Gen2 and does not supported Gen3.
>> Hence, it is restricted using the DTSI property.
> 
> Ideally this needs to be negotiated between the PCIe host and PHY
> drivers.

Would it not fall back automatically?

In any case, I'm fine with this, so long as there's a comment above it

Konrad