linux-kernel - Re: [RFC,v14 4/5] arm64: tegra: Add PCIe port node with PCIe WAKE# for C1 controller

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Message-ID: <6e282e1b-39d2-4a08-bdd4-a9d02b2b7f74@nvidia.com>
Date:   Thu, 7 Dec 2023 14:23:46 +0530
From:   Manikanta Maddireddy <mmaddireddy@...dia.com>
To:     Manivannan Sadhasivam <mani@...nel.org>
Cc:     bhelgaas@...gle.com, thierry.reding@...il.com, petlozup@...dia.com,
        rafael.j.wysocki@...el.com, lpieralisi@...nel.org, robh@...nel.org,
        jeffy.chen@...k-chips.com, krzysztof.kozlowski+dt@...aro.org,
        jonathanh@...dia.com, dmitry.osipenko@...labora.com,
        viresh.kumar@...aro.org, gregkh@...uxfoundation.org,
        steven.price@....com, kw@...ux.com, linux-pci@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-tegra@...r.kernel.org, linux-pm@...r.kernel.org,
        vidyas@...dia.com
Subject: Re: [RFC,v14 4/5] arm64: tegra: Add PCIe port node with PCIe WAKE#
 for C1 controller


On 07-12-2023 13:29, Manivannan Sadhasivam wrote:
> External email: Use caution opening links or attachments
>
>
> On Thu, Dec 07, 2023 at 12:54:04PM +0530, Manikanta Maddireddy wrote:
>> On 06-12-2023 21:06, Manivannan Sadhasivam wrote:
>>> External email: Use caution opening links or attachments
>>>
>>>
>>> On Wed, Feb 08, 2023 at 04:46:44PM +0530, Manikanta Maddireddy wrote:
>>>> Add PCIe port node under the PCIe controller-1 device tree node to support
>>>> PCIe WAKE# interrupt for WiFi.
>>>>
>>>> Signed-off-by: Manikanta Maddireddy <mmaddireddy@...dia.com>
>>>> ---
>>>>
>>>> Changes in v14:
>>>> New patch in the series to support PCIe WAKE# in NVIDIA Jetson AGX Orin.
>>>>
>>>>    .../dts/nvidia/tegra234-p3737-0000+p3701-0000.dts     | 11 +++++++++++
>>>>    1 file changed, 11 insertions(+)
>>>>
>>>> diff --git a/arch/arm64/boot/dts/nvidia/tegra234-p3737-0000+p3701-0000.dts b/arch/arm64/boot/dts/nvidia/tegra234-p3737-0000+p3701-0000.dts
>>>> index 8a9747855d6b..9c89be263141 100644
>>>> --- a/arch/arm64/boot/dts/nvidia/tegra234-p3737-0000+p3701-0000.dts
>>>> +++ b/arch/arm64/boot/dts/nvidia/tegra234-p3737-0000+p3701-0000.dts
>>>> @@ -2147,6 +2147,17 @@ pcie@...00000 {
>>>>
>>>>                         phys = <&p2u_hsio_3>;
>>>>                         phy-names = "p2u-0";
>>>> +
>>>> +                     pci@0,0 {
>>>> +                             reg = <0x0000 0 0 0 0>;
>>>> +                             #address-cells = <3>;
>>>> +                             #size-cells = <2>;
>>>> +                             ranges;
>>>> +
>>>> +                             interrupt-parent = <&gpio>;
>>>> +                             interrupts = <TEGRA234_MAIN_GPIO(L, 2) IRQ_TYPE_LEVEL_LOW>;
>>>> +                             interrupt-names = "wakeup";
>>> WAKE# should be part of the PCIe controller, not device. And the interrupt name
>>> should be "wake".
>>>
>>> - Mani
>> Hi,
>>
>> Please refer to the discussion in below link, WAKE# is per PCI bridge.
>> https://patchwork.ozlabs.org/project/linux-pci/patch/20171226020806.32710-2-jeffy.chen@rock-chips.com/
>>
> PCIe Host controller (RC) usually represents host bridge + PCI-PCI bridge. We do
> not represent the PCI-PCI bridge in devicetree for any platforms, but only RC as
> a whole.
>
> Moreover, PERST# is already defined in RC node. So it becomes confusing if
> WAKE# is defined in a child node representing bridge.
>
> So please move WAKE# to RC node.
>
> - Mani

Hi,

We can define PCI-PCI bridge in device tree, refer to below device tree 
which has 3 ports under a controller,
with PERST#(reset-gpios) defined per port.

https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tree/arch/arm64/boot/dts/apple/t8103.dtsi#n749

Also, of_pci_setup_wake_irq() in below patch is parsing "wakeup" from 
PCI bridge, not from the host bridge.
https://patchwork.ozlabs.org/project/linux-pci/patch/20230208111645.3863534-4-mmaddireddy@nvidia.com/

If a controller has only one port it has to define a PCI bridge under 
controller device tree node and
add wakeup interrupt property, refer to below patch from original author.

https://www.spinics.net/lists/linux-pci/msg135569.html

Thanks,
Manikanta
>
>> I carried wakeup name defined in previous version, but wake seems to be
>> sufficient.
>>
>> Thanks,
>> Manikanta
>>>> +                     };
>>>>                 };
>>>>
>>>>                 pcie@...60000 {
>>>> --
>>>> 2.25.1
>>>>
>>> --
>>> மணிவண்ணன் சதாசிவம்
> --
> மணிவண்ணன் சதாசிவம்