linux-kernel - Re: [PATCH v3 3/3] arm64: qcom: sc7280: Move phy, perst to root port node

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Message-ID: <uz4muqjo3mhso3wlzfl6hmo3c6nns2ekfin76y2443tt5nzfcs@5j66ihrw2nvc>
Date: Tue, 3 Jun 2025 13:37:30 +0530
From: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To: Krishna Chaitanya Chundru <krishna.chundru@....qualcomm.com>
Cc: Lorenzo Pieralisi <lpieralisi@...nel.org>, 
	Krzysztof Wilczyński <kw@...ux.com>, Rob Herring <robh@...nel.org>, 
	Bjorn Helgaas <bhelgaas@...gle.com>, Krzysztof Kozlowski <krzk+dt@...nel.org>, 
	Conor Dooley <conor+dt@...nel.org>, Bjorn Andersson <andersson@...nel.org>, 
	Konrad Dybcio <konradybcio@...nel.org>, cros-qcom-dts-watchers@...omium.org, 
	linux-arm-msm@...r.kernel.org, linux-pci@...r.kernel.org, devicetree@...r.kernel.org, 
	linux-kernel@...r.kernel.org, quic_vbadigan@...cinc.com, quic_mrana@...cinc.com
Subject: Re: [PATCH v3 3/3] arm64: qcom: sc7280: Move phy, perst to root port
 node

On Tue, Jun 03, 2025 at 01:05:17PM +0530, Krishna Chaitanya Chundru wrote:
> 
> 
> On 6/3/2025 12:22 PM, Manivannan Sadhasivam wrote:
> > On Tue, Jun 03, 2025 at 12:03:01PM +0530, Krishna Chaitanya Chundru wrote:
> > > 
> > > 
> > > On 6/1/2025 12:35 PM, Manivannan Sadhasivam wrote:
> > > > On Sat, Apr 19, 2025 at 10:49:26AM +0530, Krishna Chaitanya Chundru wrote:
> > > > > There are many places we agreed to move the wake and perst gpio's
> > > > > and phy etc to the pcie root port node instead of bridge node[1].
> > > > 
> > > > Same comment as binding patch applies here.
> > > > 
> > > > > 
> > > > > So move the phy, phy-names, wake-gpio's in the root port.
> > > > 
> > > > You are not moving any 'wake-gpios' property.
> > > > 
> > > ack I will remove it.
> > > > > There is already reset-gpio defined for PERST# in pci-bus-common.yaml,
> > > > > start using that property instead of perst-gpio.
> > > > > 
> > > > > [1] https://lore.kernel.org/linux-pci/20241211192014.GA3302752@bhelgaas/
> > > > > 
> > > > > Signed-off-by: Krishna Chaitanya Chundru <krishna.chundru@....qualcomm.com>
> > > > > ---
> > > > >    arch/arm64/boot/dts/qcom/qcs6490-rb3gen2.dts   | 5 ++++-
> > > > >    arch/arm64/boot/dts/qcom/sc7280-herobrine.dtsi | 5 ++++-
> > > > >    arch/arm64/boot/dts/qcom/sc7280-idp.dtsi       | 5 ++++-
> > > > >    arch/arm64/boot/dts/qcom/sc7280.dtsi           | 6 ++----
> > > > >    4 files changed, 14 insertions(+), 7 deletions(-)
> > > > > 
> > > > > diff --git a/arch/arm64/boot/dts/qcom/qcs6490-rb3gen2.dts b/arch/arm64/boot/dts/qcom/qcs6490-rb3gen2.dts
> > > > > index 7a36c90ad4ec8b52f30b22b1621404857d6ef336..3dd58986ad5da0f898537a51715bb5d0fecbe100 100644
> > > > > --- a/arch/arm64/boot/dts/qcom/qcs6490-rb3gen2.dts
> > > > > +++ b/arch/arm64/boot/dts/qcom/qcs6490-rb3gen2.dts
> > > > > @@ -709,8 +709,11 @@ &mdss_edp_phy {
> > > > >    	status = "okay";
> > > > >    };
> > > > > +&pcie1_port0 {
> > > > > +	reset-gpios = <&tlmm 2 GPIO_ACTIVE_LOW>;
> > > > > +};
> > > > > +
> > > > >    &pcie1 {
> > > > > -	perst-gpios = <&tlmm 2 GPIO_ACTIVE_LOW>;
> > > > >    	pinctrl-0 = <&pcie1_reset_n>, <&pcie1_wake_n>;
> > > > >    	pinctrl-names = "default";
> > > > 
> > > > What about the pinctrl properties? They should also be moved.
> > > > 
> > > pinctrl can still reside in the host bridge node, which has
> > > all the gpio's for all the root ports. If we move them to the
> > > root ports we need to explicitly apply pinctrl settings as these
> > > not tied with the driver yet.
> > > 
> > 
> > If the DT node is associated with a device, then the driver core should bind the
> > pinctrl pins and configure them. Is that not happening here?
> The root node will not be associated with the driver until enumeration,
> the controller drivers needs these to be configured before enumeration.
> 

Hmm. I'm working on moving the PERST# deassert to pwrctrl drivers, but even then
the PERST# assert needs to happen in the controller driver for initialization.
And moving them to root port node would cause the pin state to be changed
in-between. So I agree, let's leave them in controller node itself.

- Mani

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