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

[Thierry Reding <thierry.reding@gmail.com>]

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On Thu, Feb 09, 2023 at 10:53:25AM +0000, Petlozu Pravareshwar wrote:
> > 
> > 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@nvidia.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@14100000 {
> > > > >   			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

Heh... nicely self-owned =). You're right, no need for the detour in DT
with those, the GPIO driver will hook up the IRQ hierarchy itself. We
already do this for the "power" key in the various gpio-keys, so it
should work fine.

Sorry for the noise,
Thierry

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