Message-ID: <Z684nUnDX4Sb98rQ@probook>
Date: Fri, 14 Feb 2025 12:35:41 +0000
From: J. Neuschäfer <j.ne@...teo.net>
To: Frank Li <Frank.li@....com>
Cc: j.ne@...teo.net, devicetree@...r.kernel.org,
	linuxppc-dev@...ts.ozlabs.org,
	Krzysztof Kozlowski <krzk@...nel.org>, imx@...ts.linux.dev,
	Scott Wood <oss@...error.net>,
	Madhavan Srinivasan <maddy@...ux.ibm.com>,
	Michael Ellerman <mpe@...erman.id.au>,
	Nicholas Piggin <npiggin@...il.com>,
	Christophe Leroy <christophe.leroy@...roup.eu>,
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	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Damien Le Moal <dlemoal@...nel.org>,
	Niklas Cassel <cassel@...nel.org>,
	Herbert Xu <herbert@...dor.apana.org.au>,
	"David S. Miller" <davem@...emloft.net>, Lee Jones <lee@...nel.org>,
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	Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	J. Neuschäfer <j.neuschaefer@....net>,
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	Guenter Roeck <linux@...ck-us.net>, Mark Brown <broonie@...nel.org>,
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	linux-mtd@...ts.infradead.org
Subject: Re: [PATCH v2 05/12] dt-bindings: dma: Convert fsl,elo*-dma to YAML

On Mon, Feb 10, 2025 at 02:39:13PM -0500, Frank Li wrote:
> On Fri, Feb 07, 2025 at 10:30:22PM +0100, J. Neuschäfer via B4 Relay wrote:
> > From: "J. Neuschäfer" <j.ne@...teo.net>
> >
> > The devicetree bindings for Freescale DMA engines have so far existed as
> > a text file. This patch converts them to YAML, and specifies all the
> > compatible strings currently in use in arch/powerpc/boot/dts.
> >
> > Signed-off-by: J. Neuschäfer <j.ne@...teo.net>
> > ---
> >
> > V2:
> > - remove unnecessary multiline markers
> > - fix additionalProperties to always be false
> > - add description/maxItems to interrupts
> > - add missing #address-cells/#size-cells properties
> > - convert "Note on DMA channel compatible properties" to YAML by listing
> >   fsl,ssi-dma-channel as a valid compatible value
> > - fix property ordering in examples: compatible and reg come first
> > - add missing newlines in examples
> > - trim subject line (remove "bindings")
> > ---
> >  .../devicetree/bindings/dma/fsl,elo-dma.yaml       | 140 ++++++++++++++
> >  .../devicetree/bindings/dma/fsl,elo3-dma.yaml      | 123 +++++++++++++
> >  .../devicetree/bindings/dma/fsl,eloplus-dma.yaml   | 134 ++++++++++++++
> >  .../devicetree/bindings/powerpc/fsl/dma.txt        | 204 ---------------------
> >  4 files changed, 397 insertions(+), 204 deletions(-)
[...]
> > +  reg:
> > +    maxItems: 1
> > +    description:
> > +      DMA General Status Register, i.e. DGSR which contains status for
> > +      all the 4 DMA channels.
> 
> needn't maxItems
> items:
>   - description: DMA ...

Good point, I'll do that.

> 
> > +
> > +  cell-index:
> > +    $ref: /schemas/types.yaml#/definitions/uint32
> > +    description: Controller index. 0 for controller @ 0x8100.
> > +
> > +  ranges: true
> > +
> > +  "#address-cells":
> > +    const: 1
> > +
> > +  "#size-cells":
> > +    const: 1
> > +
> > +  interrupts:
> > +    maxItems: 1
> > +    description: Controller interrupt.
> 
> Needn't description because no any additional informaiton.

True.

> 
> > +
> > +required:
> > +  - compatible
> > +  - reg
[...]
> > +additionalProperties: false
> 
> Need ref to dma-common.yaml?

Sounds good, but I'm not sure what to do about the #dma-cells property,
which is required by dma-common.yaml.

There aren't many examples of DMA channels being explicitly declared in
device trees. One example that I could find is the the xilinx_dma.txt
binding:


	axi_vdma_0: axivdma@...30000 {
		compatible = "xlnx,axi-vdma-1.00.a";
		#dma_cells = <1>;
		reg = < 0x40030000 0x10000 >;
		dma-ranges = <0x00000000 0x00000000 0x40000000>;
		xlnx,num-fstores = <0x8>;
		xlnx,flush-fsync = <0x1>;
		xlnx,addrwidth = <0x20>;
		clocks = <&clk 0>, <&clk 1>, <&clk 2>, <&clk 3>, <&clk 4>;
		clock-names = "s_axi_lite_aclk", "m_axi_mm2s_aclk", "m_axi_s2mm_aclk",
			      "m_axis_mm2s_aclk", "s_axis_s2mm_aclk";
		dma-channel@...30000 {
			compatible = "xlnx,axi-vdma-mm2s-channel";
			interrupts = < 0 54 4 >;
			xlnx,datawidth = <0x40>;
		};
		dma-channel@...30030 {
			compatible = "xlnx,axi-vdma-s2mm-channel";
			interrupts = < 0 53 4 >;
			xlnx,datawidth = <0x40>;
		};
	};

	...

	vdmatest_0: vdmatest@0 {
		compatible ="xlnx,axi-vdma-test-1.00.a";
		dmas = <&axi_vdma_0 0
			&axi_vdma_0 1>;
		dma-names = "vdma0", "vdma1";
	};

It has #dma_cells (I'm sure #dma-cells was intended) on the controller.


Another example is in arch/powerpc/boot/dts/fsl/p1022si-post.dtsi:

	dma@...0 {
		dma00: dma-channel@0 {
			compatible = "fsl,ssi-dma-channel";
		};
		dma01: dma-channel@80 {
			compatible = "fsl,ssi-dma-channel";
		};
	};

	...

	ssi@...00 {
		compatible = "fsl,mpc8610-ssi";
		cell-index = <0>;
		reg = <0x15000 0x100>;
		interrupts = <75 2 0 0>;
		fsl,playback-dma = <&dma00>;
		fsl,capture-dma = <&dma01>;
		fsl,fifo-depth = <15>;
	};


There, the DMA channels are used directly and without additional
information (i.e. #dma-cells = <0>, althought it isn't specified).


> > +        dma-channel@0 {
> > +            compatible = "fsl,mpc8349-dma-channel", "fsl,elo-dma-channel";
> > +            reg = <0 0x80>;
> > +            cell-index = <0>;
> > +            interrupt-parent = <&ipic>;
> > +            interrupts = <71 8>;
> 
> '8',  use predefine MACRO for irq type.

Good catch, will do

> 
> Frank

Thanks for your review!
J. Neuschäfer

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