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Date: Thu, 8 Feb 2024 14:34:47 -0500
From: Frank Li <Frank.li@nxp.com>
To: Conor Dooley <conor@kernel.org>
Cc: Bjorn Helgaas <bhelgaas@google.com>,
	Lorenzo Pieralisi <lpieralisi@kernel.org>,
	Krzysztof =?utf-8?Q?Wilczy=C5=84ski?= <kw@linux.com>,
	Rob Herring <robh@kernel.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
	Conor Dooley <conor+dt@kernel.org>,
	"open list:PCI SUBSYSTEM" <linux-pci@vger.kernel.org>,
	"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" <devicetree@vger.kernel.org>,
	open list <linux-kernel@vger.kernel.org>, imx@lists.linux.dev
Subject: Re: [PATCH 1/1] dt-bindings: pci: layerscape-pci: Convert to yaml
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On Thu, Feb 08, 2024 at 07:12:47PM +0000, Conor Dooley wrote:
> On Wed, Feb 07, 2024 at 12:49:19PM -0500, Frank Li wrote:
> > On Wed, Feb 07, 2024 at 05:17:55PM +0000, Conor Dooley wrote:
> > > Hey Frank,
> > > 
> > > On Wed, Feb 07, 2024 at 01:24:02AM -0500, Frank Li wrote:
> > > > Convert layerscape pcie bind document to yaml file.
> > > > 
> > > > Signed-off-by: Frank Li <Frank.Li@nxp.com>
> > > > ---
> > > >  .../bindings/pci/fsl,layerscape-pcie-ep.yaml  |  84 +++++++++
> > > >  .../bindings/pci/fsl,layerscape-pcie.yaml     | 163 ++++++++++++++++++
> > > >  .../bindings/pci/layerscape-pci.txt           |  79 ---------
> > > >  3 files changed, 247 insertions(+), 79 deletions(-)
> > > >  create mode 100644 Documentation/devicetree/bindings/pci/fsl,layerscape-pcie-ep.yaml
> > > >  create mode 100644 Documentation/devicetree/bindings/pci/fsl,layerscape-pcie.yaml
> > > >  delete mode 100644 Documentation/devicetree/bindings/pci/layerscape-pci.txt
> > > > 
> > > > diff --git a/Documentation/devicetree/bindings/pci/fsl,layerscape-pcie-ep.yaml b/Documentation/devicetree/bindings/pci/fsl,layerscape-pcie-ep.yaml
> > > > new file mode 100644
> > > > index 0000000000000..3b592c820eb4c
> > > > --- /dev/null
> > > > +++ b/Documentation/devicetree/bindings/pci/fsl,layerscape-pcie-ep.yaml
> > > > @@ -0,0 +1,84 @@
> > > > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > > > +%YAML 1.2
> > > > +---
> > > > +$id: http://devicetree.org/schemas/pci/fsl,layerscape-pcie-ep.yaml#
> > > > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > > > +
> > > > +title: Freescale Layerscape PCIe controller
> > > > +
> > > > +maintainers:
> > > > +  - Frank Li <Frank.Li@nxp.com>
> > > > +
> > > > +description: |+
> > > 
> > > Are you sure that you need this chomping operator?
> > > 
> > > > +  This PCIe endpoint controller is based on the Synopsys DesignWare PCIe IP
> > > 
> > > > +  and thus inherits all the common properties defined in snps,dw-pcie-ep.yaml.
> > > 
> > > You shouldn't need this statement given you have the ref: below.
> > > 
> > > > +
> > > > +  This controller derives its clocks from the Reset Configuration Word (RCW)
> > > > +  which is used to describe the PLL settings at the time of chip-reset.
> > > > +
> > > > +  Also as per the available Reference Manuals, there is no specific 'version'
> > > > +  register available in the Freescale PCIe controller register set,
> > > > +  which can allow determining the underlying DesignWare PCIe controller version
> > > > +  information.
> > > > +
> > > > +properties:
> > > > +  compatible:
> > > > +    enum:
> > > > +      - fsl,ls2088a-pcie-ep
> > > > +      - fsl,ls1088a-pcie-ep
> > > > +      - fsl,ls1046a-pcie-ep
> > > > +      - fsl,ls1028a-pcie-ep
> > > > +      - fsl,lx2160ar2-pcie-ep
> > > 
> > > Where did the fallback compatible go?
> > 
> > So far, no fallback compatible needed now. each devices already have its
> > compatible string.
> 
> It used to exist though, have you checked that u-boot or *bsd etc do not
> use the fallback compatible? You also need to mention your justification
> for removing it in the commit message.

This commit just convert binding doc from txt to yaml. I just make sure
which equal to what descript in txt. If there are someting wrong in "uboot"
or "bsd", we can fixed it later. I checked driver code. exited dts tree
under kernel, which use unexited fallback compatible string
"fsl, lx-pcie-ep", which should be removed at dts file.

> 
> > > > +
> > > > +  reg:
> > > > +    maxItems: 2
> > > > +
> > > > +  reg-names:
> > > > +    items:
> > > > +      - const: regs
> > > > +      - const: addr_space
> > > 
> > > The example uses "regs" and "config". Where did addr_space come from?
> > 
> > Example just show pcie-host part. Not show pcie-ep part.
> > pcie-ep part need 'addr_space'.
> 
> Okay. Again, please mention where this is coming from.

Ideally it comes from snsp,dwc-pcie-ep.yaml. but it is use 'dbi' instead
of 'regs'. It needs extra effort to make driver code algin common
snps,dwc-pcie-ep.yaml, and update exist all dts files.

I think it will be deleted soon. 

> 
> > 
> > > 
> > > > +  fsl,pcie-scfg:
> > > > +    $ref: /schemas/types.yaml#/definitions/phandle
> > > > +    description: A phandle to the SCFG device node. The second entry is the
> > > > +      physical PCIe controller index starting from '0'. This is used to get
> > > > +      SCFG PEXN registers.
> > > > +
> > > > +  dma-coherent:
> > > 
> > > dma-coherent: true
> > > 
> > > > +    $ref: /schemas/types.yaml#/definitions/flag
> > > > +    description: Indicates that the hardware IP block can ensure the coherency
> > > > +      of the data transferred from/to the IP block. This can avoid the software
> > > > +      cache flush/invalid actions, and improve the performance significantly.
> > > > +
> > > > +  big-endian:
> > > > +    $ref: /schemas/types.yaml#/definitions/flag
> > > > +    description: If the PEX_LUT and PF register block is in big-endian, specify
> > > > +      this property.
> > > > +
> > > > +required:
> > > > +  - compatible
> > > > +  - reg
> > > > +  - reg-names
> > > 
> > > This was not previously required, why is it required now?
> > 
> > Actually its needed.
> 
> Well, if it wasn't, I'd hope that you wouldn't be making it required.
> But I asked /why/ and you've not given a reason. Please mention the why
> in your commit message for v2.

Sorry, I just sent v2 before see this. According to driver code, it is
needed. Please check v2, I will update at v3. 


> 
> Cheers,
> Conor.
>