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

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Date:   Thu, 9 Feb 2023 10:53:25 +0000
From:   Petlozu Pravareshwar <petlozup@...dia.com>
To:     Thierry Reding <thierry.reding@...il.com>,
        Manikanta Maddireddy <mmaddireddy@...dia.com>
CC:     "bhelgaas@...gle.com" <bhelgaas@...gle.com>,
        "rafael.j.wysocki@...el.com" <rafael.j.wysocki@...el.com>,
        "lpieralisi@...nel.org" <lpieralisi@...nel.org>,
        "robh@...nel.org" <robh@...nel.org>,
        "jeffy.chen@...k-chips.com" <jeffy.chen@...k-chips.com>,
        "krzysztof.kozlowski+dt@...aro.org" 
        <krzysztof.kozlowski+dt@...aro.org>,
        Jonathan Hunter <jonathanh@...dia.com>,
        "dmitry.osipenko@...labora.com" <dmitry.osipenko@...labora.com>,
        "viresh.kumar@...aro.org" <viresh.kumar@...aro.org>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "steven.price@....com" <steven.price@....com>,
        "kw@...ux.com" <kw@...ux.com>,
        "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-tegra@...r.kernel.org" <linux-tegra@...r.kernel.org>,
        "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
        Vidya Sagar <vidyas@...dia.com>
Subject: RE: [RFC,v14 4/5] arm64: tegra: Add PCIe port node with PCIe WAKE#
 for C1 controller

> 
> On Wed, Feb 08, 2023 at 05:43:35PM +0530, Manikanta Maddireddy wrote:
> >
> > On 2/8/2023 5:07 PM, Thierry Reding wrote:
> > > 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.dt
> > > > +++ s
> > > > @@ -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";
> > > > +			};
> > > Don't we need to wire this to the PMC interrupt controller and the
> > > wake event corresponding to the L2 GPIO? Otherwise none of the wake
> > > logic in PMC will get invoked.
> > >
> > > Thierry
> > PCIe wake is gpio based not pmc, only wake support is provided by PMC
> > controller.
> > I verified this patch and able to wake up Tegra from suspend.
> > Petlozu, correct me if my understanding is wrong.
> 
> The way that this usually works is that you need to use something like
> this:
> 
> 	interrupt-parent = <&pmc>;
> 	interrupts = <1 IRQ_TYPE_LEVEL_LOW>;
> 	interrupt-names = "wakeup";
> 
> This will then cause the PMC's interrupt chip callbacks to setup all the wake-
> related interrupts and use the internal wake event tables to forward the
> GPIO/IRQ corresponding to the PMC wake event to the GPIO controller or
> GIC, respectively.
> 
> If you use &gpio as the interrupt parent, none of the PMC logic will be
> invoked, so unless this is somehow set up correctly by default, the PMC
> wouldn't be able to wake up the system.
> 
> Thierry
Thierry,
Since PMC's IRQ domain is made as parent of GPIO controller's IRQ domain,
I think, for GPIO based wakes setting &gpio as the interrupt parent can still
invoke PMC logic to program the required registers to enable such wakes.
Related commit in this regard:
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/drivers/gpio/gpio-tegra186.c?id=2a36550567307b881ce570a81189682ae1c9d08d

Thanks.