RE: [PATCH 1/4] dt-bingings: PCI: Remove the num-lanes from Required properties

From: "Z.q. Hou" <zhiqiang.hou@nxp.com>
To: Andrew Murray <andrew.murray@arm.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
Date: Tue, 13 Aug 2019 03:07:22 +0000	[thread overview]
Message-ID: <DB8PR04MB67476309D3F7E30FE35C47DF84D20@DB8PR04MB6747.eurprd04.prod.outlook.com> (raw)
In-Reply-To: <20190812084517.GW56241@e119886-lin.cambridge.arm.com>

Hi Andrew,

Thanks a lot for your comments!

> -----Original Message-----
> From: Andrew Murray <andrew.murray@arm.com>
> Sent: 2019年8月12日 16:45
> To: Z.q. Hou <zhiqiang.hou@nxp.com>
> Cc: linux-pci@vger.kernel.org; devicetree@vger.kernel.org;
> linux-kernel@vger.kernel.org; gustavo.pimentel@synopsys.com;
> jingoohan1@gmail.com; bhelgaas@google.com; robh+dt@kernel.org;
> mark.rutland@arm.com; shawnguo@kernel.org; Leo Li
> <leoyang.li@nxp.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
> 
> 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".

Agree and will change in v2.

> 
> 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?

Kishon, please help to answer this query?

Thanks,
Zhiqiang

> 
> 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
> >