linux-kernel - Re: [PATCH v8 2/7] arm64: dts: qcom: sm8450: Add interconnect path to PCIe node

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Date: Sat, 6 Apr 2024 22:48:29 +0530
From: Krishna Chaitanya Chundru <quic_krichai@...cinc.com>
To: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
        Konrad Dybcio
	<konrad.dybcio@...aro.org>
CC: Bjorn Andersson <andersson@...nel.org>,
        Lorenzo Pieralisi
	<lpieralisi@...nel.org>,
        Krzysztof Wilczyński
	<kw@...ux.com>,
        Rob Herring <robh@...nel.org>, Bjorn Helgaas
	<bhelgaas@...gle.com>,
        Krzysztof Kozlowski
	<krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        "Rob
 Herring" <robh+dt@...nel.org>,
        Johan Hovold <johan+linaro@...nel.org>,
        "Brian
 Masney" <bmasney@...hat.com>,
        Georgi Djakov <djakov@...nel.org>, <linux-arm-msm@...r.kernel.org>,
        <linux-pci@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <vireshk@...nel.org>,
        <quic_vbadigan@...cinc.com>, <quic_skananth@...cinc.com>,
        <quic_nitegupt@...cinc.com>, <quic_parass@...cinc.com>
Subject: Re: [PATCH v8 2/7] arm64: dts: qcom: sm8450: Add interconnect path to
 PCIe node



On 4/5/2024 1:10 PM, Manivannan Sadhasivam wrote:
> On Wed, Mar 06, 2024 at 05:04:54PM +0100, Konrad Dybcio wrote:
>>
>>
>> On 3/2/24 04:59, Krishna chaitanya chundru wrote:
>>> Add pcie-mem & cpu-pcie interconnect path to the PCIe nodes.
>>>
>>> Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
>>> Signed-off-by: Krishna chaitanya chundru <quic_krichai@...cinc.com>
>>> ---
>>>    arch/arm64/boot/dts/qcom/sm8450.dtsi | 8 ++++++++
>>>    1 file changed, 8 insertions(+)
>>>
>>> diff --git a/arch/arm64/boot/dts/qcom/sm8450.dtsi b/arch/arm64/boot/dts/qcom/sm8450.dtsi
>>> index 01e4dfc4babd..6b1d2e0d9d14 100644
>>> --- a/arch/arm64/boot/dts/qcom/sm8450.dtsi
>>> +++ b/arch/arm64/boot/dts/qcom/sm8450.dtsi
>>> @@ -1781,6 +1781,10 @@ pcie0: pcie@...0000 {
>>>    					<0 0 0 3 &intc 0 0 0 151 IRQ_TYPE_LEVEL_HIGH>, /* int_c */
>>>    					<0 0 0 4 &intc 0 0 0 152 IRQ_TYPE_LEVEL_HIGH>; /* int_d */
>>> +			interconnects = <&pcie_noc MASTER_PCIE_0 0 &mc_virt SLAVE_EBI1 0>,
>>
>> Please use QCOM_ICC_TAG_ALWAYS.
>>
>>> +					<&gem_noc MASTER_APPSS_PROC 0 &config_noc SLAVE_PCIE_0 0>;
>>
>> And this path could presumably be demoted to QCOM_ICC_TAG_ACTIVE_ONLY?
>>
> 
> I think it should be fine since there would be no register access done while the
> RPMh is put into sleep state. Krishna, can you confirm that by executing the CX
> shutdown with QCOM_ICC_TAG_ACTIVE_ONLY vote for cpu-pcie path on any supported
> platform?
> 
> But if we do such change, then it should also be applied to other SoCs.
> 
> - Mani
>
we don't a have platform to test this now, we will keep
QCOM_ICC_TAG_ALWAYS for now.

- Krishna Chaitanya.