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Date:   Wed, 18 Nov 2020 21:25:52 +0530
From:   Vinod Koul <vkoul@kernel.org>
To:     Amireddy Mallikarjuna reddy <mallikarjunax.reddy@linux.intel.com>
Cc:     dmaengine@vger.kernel.org, devicetree@vger.kernel.org,
        robh+dt@kernel.org, linux-kernel@vger.kernel.org,
        andriy.shevchenko@intel.com, chuanhua.lei@linux.intel.com,
        cheol.yong.kim@intel.com, qi-ming.wu@intel.com,
        malliamireddy009@gmail.com, peter.ujfalusi@ti.com
Subject: Re: [PATCH v9 1/2] dt-bindings: dma: Add bindings for Intel LGM SoC
Message-ID: <20201118155552.GV50232@vkoul-mobl>
References: <cover.1605158930.git.mallikarjunax.reddy@linux.intel.com>
 <bfe586ac62080d14759bda22ebf1de1a1fa9c09d.1605158930.git.mallikarjunax.reddy@linux.intel.com>
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On 12-11-20, 13:38, Amireddy Mallikarjuna reddy wrote:
> Add DT bindings YAML schema for DMA controller driver
> of Lightning Mountain (LGM) SoC.
> 
> Signed-off-by: Amireddy Mallikarjuna reddy <mallikarjunax.reddy@linux.intel.com>
> ---
> v1:
> - Initial version.
> 
> v2:
> - Fix bot errors.
> 
> v3:
> - No change.
> 
> v4:
> - Address Thomas langer comments
>   - use node name pattern as dma-controller as in common binding.
>   - Remove "_" (underscore) in instance name.
>   - Remove "port-" and "chan-" in attribute name for both 'dma-ports' & 'dma-channels' child nodes.
> 
> v5:
> - Moved some of the attributes in 'dma-ports' & 'dma-channels' child nodes to dma client/consumer side as cells in 'dmas' properties.
> 
> v6:
> - Add additionalProperties: false
> - completely removed 'dma-ports' and 'dma-channels' child nodes.
> - Moved channel dt properties to client side dmas.
> - Use standard dma-channels and dma-channel-mask properties.
> - Documented reset-names
> - Add description for dma-cells
> 
> v7:
> - modified compatible to oneof
> - Reduced number of dma-cells to 3
> - Fine tune the description of some properties.
> 
> v7-resend:
> - rebase to 5.10-rc1
> 
> v8:
> - rebased to 5.10-rc3
> - Fixing the bot issues (wrong indentation)
> 
> v9:
> - rebased to 5.10-rc3
> - Use 'enum' instead of oneOf+const
> - Drop '#dma-cells' in required:, already covered in dma-common.yaml
> - Drop nodename Already covered by dma-controller.yaml
> ---
>  .../devicetree/bindings/dma/intel,ldma.yaml        | 130 +++++++++++++++++++++
>  1 file changed, 130 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/dma/intel,ldma.yaml
> 
> diff --git a/Documentation/devicetree/bindings/dma/intel,ldma.yaml b/Documentation/devicetree/bindings/dma/intel,ldma.yaml
> new file mode 100644
> index 000000000000..c06281a10178
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/dma/intel,ldma.yaml
> @@ -0,0 +1,130 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/dma/intel,ldma.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Lightning Mountain centralized low speed DMA and high speed DMA controllers.
> +
> +maintainers:
> +  - chuanhua.lei@intel.com
> +  - mallikarjunax.reddy@intel.com
> +
> +allOf:
> +  - $ref: "dma-controller.yaml#"
> +
> +properties:
> +  compatible:
> +    enum:
> +      - intel,lgm-cdma
> +      - intel,lgm-dma2tx
> +      - intel,lgm-dma1rx
> +      - intel,lgm-dma1tx
> +      - intel,lgm-dma0tx
> +      - intel,lgm-dma3
> +      - intel,lgm-toe-dma30
> +      - intel,lgm-toe-dma31
> +
> +  reg:
> +    maxItems: 1
> +
> +  "#dma-cells":
> +    const: 3
> +    description:
> +      The first cell is the peripheral's DMA request line.
> +      The second cell is the peripheral's (port) number corresponding to the channel.
> +      The third cell is the burst length of the channel.
> +
> +  dma-channels:
> +    minimum: 1
> +    maximum: 16
> +
> +  dma-channel-mask:
> +    maxItems: 1
> +
> +  clocks:
> +    maxItems: 1
> +
> +  resets:
> +    maxItems: 1
> +
> +  reset-names:
> +    items:
> +      - const: ctrl
> +
> +  interrupts:
> +    maxItems: 1
> +
> +  intel,dma-poll-cnt:
> +    $ref: /schemas/types.yaml#definitions/uint32
> +    description:
> +      DMA descriptor polling counter is used to control the poling mechanism

s/poling/polling

> +      for the descriptor fetching for all channels.
> +
> +  intel,dma-byte-en:
> +    type: boolean
> +    description:
> +      DMA byte enable is only valid for DMA write(RX).
> +      Byte enable(1) means DMA write will be based on the number of dwords
> +      instead of the whole burst.

Can you explain this, also sounds you could use _maxburst values..?

> +
> +  intel,dma-drb:
> +    type: boolean
> +    description:
> +      DMA descriptor read back to make sure data and desc synchronization.
> +
> +  intel,dma-desc-in-sram:
> +    type: boolean
> +    description:
> +      DMA descritpors in SRAM or not. Some old controllers descriptors
> +      can be in DRAM or SRAM. The new ones are all in SRAM.

should that not be decided by driver..? Or is this a hw property?

> +
> +  intel,dma-orrc:
> +    $ref: /schemas/types.yaml#definitions/uint32
> +    description:
> +      DMA outstanding read counter value determine the number of
> +      ORR-Outstanding Read Request. The maximum value is 16.

How would this be used by folks..?

> +
> +  intel,dma-dburst-wr:
> +    type: boolean
> +    description:
> +      Enable RX dynamic burst write. When it is enabled, the DMA does RX dynamic burst;
> +      if it is disabled, the DMA RX will still support programmable fixed burst size of 2,4,8,16.
> +      It only applies to RX DMA and memcopy DMA.
> +
> +required:
> +  - compatible
> +  - reg

So only two are mandatory, what about the bunch of intel properties you
added above..?

> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    dma0: dma-controller@e0e00000 {
> +      compatible = "intel,lgm-cdma";
> +      reg = <0xe0e00000 0x1000>;
> +      #dma-cells = <3>;
> +      dma-channels = <16>;
> +      dma-channel-mask = <0xFFFF>;
> +      interrupt-parent = <&ioapic1>;
> +      interrupts = <82 1>;
> +      resets = <&rcu0 0x30 0>;
> +      reset-names = "ctrl";
> +      clocks = <&cgu0 80>;
> +      intel,dma-poll-cnt = <4>;
> +      intel,dma-byte-en;
> +      intel,dma-drb;
> +    };
> +  - |
> +    dma3: dma-controller@ec800000 {
> +      compatible = "intel,lgm-dma3";
> +      reg = <0xec800000 0x1000>;
> +      clocks = <&cgu0 71>;
> +      resets = <&rcu0 0x10 9>;
> +      #dma-cells = <3>;
> +      intel,dma-poll-cnt = <16>;
> +      intel,dma-desc-in-sram;
> +      intel,dma-orrc = <16>;
> +      intel,dma-byte-en;
> +      intel,dma-dburst-wr;
> +    };
> -- 
> 2.11.0

-- 
~Vinod