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Date: Mon, 18 Mar 2024 10:54:45 +0530
From: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
To: Bjorn Andersson <andersson@kernel.org>
Cc: Konrad Dybcio <konrad.dybcio@linaro.org>,
	Rob Herring <robh+dt@kernel.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
	Conor Dooley <conor+dt@kernel.org>,
	cros-qcom-dts-watchers@chromium.org, linux-arm-msm@vger.kernel.org,
	devicetree@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 09/21] arm64: dts: qcom: sc8280xp: Add PCIe bridge node
Message-ID: <20240318052445.GC2748@thinkpad>
References: <20240221-pcie-qcom-bridge-dts-v1-0-6c6df0f9450d@linaro.org>
 <20240221-pcie-qcom-bridge-dts-v1-9-6c6df0f9450d@linaro.org>
 <9d6c617a-bc3a-47c4-a988-b41b804d8cfe@linaro.org>
 <20240222053958.GF3374@thinkpad>
 <26mic7smm2aez3enydiiuul2c5yru4kmx26n4mo63nvy4bscuv@jql4hhe3gia6>
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In-Reply-To: <26mic7smm2aez3enydiiuul2c5yru4kmx26n4mo63nvy4bscuv@jql4hhe3gia6>

On Sun, Mar 17, 2024 at 10:37:15PM -0500, Bjorn Andersson wrote:
> On Thu, Feb 22, 2024 at 11:09:58AM +0530, Manivannan Sadhasivam wrote:
> > On Wed, Feb 21, 2024 at 01:39:01PM +0100, Konrad Dybcio wrote:
> > > On 21.02.2024 04:41, Manivannan Sadhasivam wrote:
> > > > On Qcom SoCs, the PCIe host bridge is connected to a single PCIe bridge
> > > > for each controller instance. Hence, add a node to represent the bridge.
> > > > 
> > > > While at it, let's remove the bridge properties from board dts as they are
> > > > now redundant.
> > > > 
> > > > Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
> > > > ---
> > > >  .../dts/qcom/sc8280xp-lenovo-thinkpad-x13s.dts     |  8 -----
> > > >  arch/arm64/boot/dts/qcom/sc8280xp.dtsi             | 40 ++++++++++++++++++++++
> > > >  2 files changed, 40 insertions(+), 8 deletions(-)
> > > > 
> > > > diff --git a/arch/arm64/boot/dts/qcom/sc8280xp-lenovo-thinkpad-x13s.dts b/arch/arm64/boot/dts/qcom/sc8280xp-lenovo-thinkpad-x13s.dts
> > > > index def3976bd5bb..f0a0115e08fa 100644
> > > > --- a/arch/arm64/boot/dts/qcom/sc8280xp-lenovo-thinkpad-x13s.dts
> > > > +++ b/arch/arm64/boot/dts/qcom/sc8280xp-lenovo-thinkpad-x13s.dts
> > > > @@ -733,14 +733,6 @@ &pcie4 {
> > > >  	status = "okay";
> > > >  
> > > >  	pcie@0 {
> > > > -		device_type = "pci";
> > > > -		reg = <0x0 0x0 0x0 0x0 0x0>;
> > > > -		#address-cells = <3>;
> > > > -		#size-cells = <2>;
> > > > -		ranges;
> > > > -
> > > > -		bus-range = <0x01 0xff>;
> > > > -
> > > >  		wifi@0 {
> > > 
> > > This doesn't seem right, pleas use a label
> > > 
> > 
> > Why? A node label is useful if we want to reference it at the root level in
> > board dts, but here it is not.
> > 
> 
> Giving the bridge a label and then adding wifi@0 as a child using that
> label in the dts is pretty much how we do for everything else.
> 
> I find this over-flattening hard to follow, but relying on child node
> names when extending the structure or adding properties have bitten us
> many times in the past.
> 
> As such, I think the desired result in the dts should be:
> 
> &pcie4 {
> 	status = "okay";
> };
> 
> &pcie4_bridge {
> 	wifi@0 {
> 		...
> 	};
> };
> 

Ok. Will change it in next version. I'm also waiting to conclude on representing
the PERST# and WAKE# properties properly in the schema [1]. Once that gets
finalized, I'll respin v2.

- Mani

[1] https://github.com/devicetree-org/dt-schema/pull/126

> Regards,
> Bjorn
> 
> > - Mani
> > 
> > -- 
> > மணிவண்ணன் சதாசிவம்

-- 
மணிவண்ணன் சதாசிவம்