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Date:   Mon, 12 Aug 2019 09:45:17 +0100
From:   Andrew Murray <andrew.murray@arm.com>
To:     "Z.q. Hou" <zhiqiang.hou@nxp.com>
Cc:     "linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
        "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "gustavo.pimentel@synopsys.com" <gustavo.pimentel@synopsys.com>,
        "jingoohan1@gmail.com" <jingoohan1@gmail.com>,
        "bhelgaas@google.com" <bhelgaas@google.com>,
        "robh+dt@kernel.org" <robh+dt@kernel.org>,
        "mark.rutland@arm.com" <mark.rutland@arm.com>,
        "shawnguo@kernel.org" <shawnguo@kernel.org>,
        Leo Li <leoyang.li@nxp.com>,
        "lorenzo.pieralisi@arm.com" <lorenzo.pieralisi@arm.com>,
        "M.h. Lian" <minghuan.lian@nxp.com>,
        Kishon Vijay Abraham I <kishon@ti.com>,
        Gabriele Paoloni <gabriele.paoloni@huawei.com>
Subject: Re: [PATCH 1/4] dt-bingings: PCI: Remove the num-lanes from Required
 properties
Message-ID: <20190812084517.GW56241@e119886-lin.cambridge.arm.com>
References: <20190812042435.25102-1-Zhiqiang.Hou@nxp.com>
 <20190812042435.25102-2-Zhiqiang.Hou@nxp.com>
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On Mon, Aug 12, 2019 at 04:22:16AM +0000, Z.q. Hou wrote:
> From: Hou Zhiqiang <Zhiqiang.Hou@nxp.com>
> 
> The num-lanes is not a mandatory property, e.g. on FSL
> Layerscape SoCs, the PCIe link training is completed
> automatically base on the selected SerDes protocol, it
> doesn't need the num-lanes to set-up the link width.
> 
> It has been added in the Optional properties. This
> patch is to remove it from the Required properties.

For clarity, maybe this paragraph can be reworded to:

"It is previously in both Required and Optional properties,
 let's remove it from the Required properties".

I don't understand why this property is previously in
both required and optional...

It looks like num-lanes was first made optional back in
2015 and removed from the Required section (907fce090253).
But then re-added back into the Required section in 2017
with the adition of bindings for EP mode (b12befecd7de).

Is num-lanes actually required for EP mode?

Thanks,

Andrew Murray

> 
> Signed-off-by: Hou Zhiqiang <Zhiqiang.Hou@nxp.com>
> ---
>  Documentation/devicetree/bindings/pci/designware-pcie.txt | 1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/Documentation/devicetree/bindings/pci/designware-pcie.txt b/Documentation/devicetree/bindings/pci/designware-pcie.txt
> index 5561a1c060d0..bd880df39a79 100644
> --- a/Documentation/devicetree/bindings/pci/designware-pcie.txt
> +++ b/Documentation/devicetree/bindings/pci/designware-pcie.txt
> @@ -11,7 +11,6 @@ Required properties:
>  	     the ATU address space.
>      (The old way of getting the configuration address space from "ranges"
>      is deprecated and should be avoided.)
> -- num-lanes: number of lanes to use
>  RC mode:
>  - #address-cells: set to <3>
>  - #size-cells: set to <2>
> -- 
> 2.17.1
>