Re: [PATCH v2 05/12] dt-bindings: dma: Convert fsl,elo*-dma to YAML

J. Neuschäfer
2025-02-14T12:35:51Z

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@posteo.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@posteo.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@40030000 {
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@40030000 {
compatible = "xlnx,axi-vdma-mm2s-channel";
interrupts = < 0 54 4 >;
xlnx,datawidth = <0x40>;
};
dma-channel@40030030 {
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@c300 {
dma00: dma-channel@0 {
compatible = "fsl,ssi-dma-channel";
};
dma01: dma-channel@80 {
compatible = "fsl,ssi-dma-channel";
};
};

...

ssi@15000 {
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