RE: [PATCH v3 1/2] dt-bindings: dma: Add bindings for intel LGM SOC

[Langer, Thomas]

Hi,

I have some questions about the binding.
Sorry I missed to ask during internal review, as I was busy with other tasks at that time.

See my questions below.

> -----Original Message-----
> From: devicetree-owner@xxxxxxxxxxxxxxx <devicetree-
> owner@xxxxxxxxxxxxxxx> On Behalf Of Amireddy Mallikarjuna reddy
> Sent: Dienstag, 23. Juni 2020 11:20
> To: dmaengine@xxxxxxxxxxxxxxx; vkoul@xxxxxxxxxx;
> devicetree@xxxxxxxxxxxxxxx; robh+dt@xxxxxxxxxx
> Cc: linux-kernel@xxxxxxxxxxxxxxx; Shevchenko, Andriy
> <andriy.shevchenko@xxxxxxxxx>; chuanhua.lei@xxxxxxxxxxxxxxx; Kim, Cheol
> Yong <cheol.yong.kim@xxxxxxxxx>; Wu, Qiming <qi-ming.wu@xxxxxxxxx>;
> malliamireddy009@xxxxxxxxx; Amireddy Mallikarjuna reddy
> <mallikarjunax.reddy@xxxxxxxxxxxxxxx>
> Subject: [PATCH v3 1/2] dt-bindings: dma: Add bindings for intel LGM SOC
> 
> Add DT bindings YAML schema for DMA controller driver
> of Lightning Mountain(LGM) SoC.
> 
> Signed-off-by: Amireddy Mallikarjuna reddy
> <mallikarjunax.reddy@xxxxxxxxxxxxxxx>
> ---
> v1:
> - Initial version.
> 
> v2:
> - Fix bot errors.
> 
> v3:
> - No change.
> ---
>  .../devicetree/bindings/dma/intel,ldma.yaml        | 428
> +++++++++++++++++++++
>  1 file changed, 428 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..d474c3e47126
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/dma/intel,ldma.yaml
> @@ -0,0 +1,428 @@
> +# 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@xxxxxxxxx
> +  - mallikarjunax.reddy@xxxxxxxxx
> +
> +properties:
> + $nodename:
> +   pattern: "^dma(@.*)?$"

Why is this not "^dma-controller(@.*)?$" as in the common binding?

> +
> + "#dma-cells":
> +   const: 1
> +
> + compatible:
> +  anyOf:
> +   - const: intel,lgm-cdma
> +   - const: intel,lgm-dma2tx
> +   - const: intel,lgm-dma1rx
> +   - const: intel,lgm-dma1tx
> +   - const: intel,lgm-dma0tx
> +   - const: intel,lgm-dma3
> +   - const: intel,lgm-toe_dma30
> +   - const: intel,lgm-toe_dma31

Why do you need so many different compatible strings?
I assume the hw blocks are mostly the same, some of them limited to rx or tx.
Why is it not possible to describe that as an attribute?

Also, is there a difference in the toe_dma instances (which should not use "_" here!)?
Or is it only the way they are connected to other hw blocks? In code they refer the same "hdma_ops" struct.

If this is only about a name to be printed in the driver, maybe a "label" or "name" attribute will be accepted?

> +
> + reg:
> +  maxItems: 1
> +
> + clocks:
> +  maxItems: 1
> +
> + resets:
> +  maxItems: 1
> +
> + interrupts:
> +  maxItems: 1
> +
> + intel,dma-poll-cnt:
> +   $ref: /schemas/types.yaml#definitions/uint32
> +   description:
> +     DMA descriptor polling counter. It may need fine tune according
> +     to the system application scenario.
> +
> + 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.
> +
> + intel,dma-drb:
> +    type: boolean
> +    description:
> +      DMA descriptor read back to make sure data and desc
> synchronization.
> +
> + intel,dma-burst:
> +    $ref: /schemas/types.yaml#definitions/uint32
> +    description:
> +       Specifiy the DMA burst size(in dwords), the valid value will be
> 8, 16, 32.
> +       Default is 16 for data path dma, 32 is for memcopy DMA.
> +
> + intel,dma-polling-cnt:
> +    $ref: /schemas/types.yaml#definitions/uint32
> +    description:
> +       DMA descriptor polling counter. It may need fine tune according
> to
> +       the system application scenario.
> +
> + 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.
> +
> + intel,dma-orrc:
> +    $ref: /schemas/types.yaml#definitions/uint32
> +    description:
> +       DMA outstanding read counter. The maximum value is 16, and it
> may
> +       need fine tune according to the system application scenarios.
> +
> + intel,dma-txendi:
> +    $ref: /schemas/types.yaml#definitions/uint32
> +    description:
> +       DMA TX endianness conversion due to SoC endianness difference.

What does this mean? The SoC endianness is know to the driver at compile time.
Is it the difference of the device connected to the dma?
As I know the dma is used also for PCIe connected devices, how can you define this in DT?

Same for other attributes below. If they depend on the connected device,
which can be external via PCIe, how can you define static configuration values in DT for it?

> +
> + intel,dma-rxendi:
> +    $ref: /schemas/types.yaml#definitions/uint32
> +    description:
> +       DMA RX endianness conversion due to SoC endianness difference.
> +
> + intel,dma-dburst-wr:
> +    type: boolean
> +    description:
> +       Enable RX dynamic burst write. It only applies to RX DMA and
> memcopy DMA.
> +
> +
> + dma-ports:
> +    type: object
> +    description:
> +       This sub-node must contain a sub-node for each DMA port.
> +    properties:
> +      '#address-cells':
> +        const: 1
> +      '#size-cells':
> +        const: 0
> +
> +    patternProperties:
> +      "^dma-ports@[0-9]+$":
> +          type: object
> +
> +          properties:
> +            reg:
> +              items:
> +                - enum: [0, 1, 2, 3, 4, 5]
> +              description:
> +                 Which port this node refers to.
> +

Some of the attributes below have "port-" in the name.
As they are in the node for "dma-ports", this is redundant.

> +            intel,port-name:
> +              $ref: /schemas/types.yaml#definitions/string-array
> +              description:
> +                 Port name of each DMA port.
> +
> +            intel,port-chans:
> +              $ref: /schemas/types.yaml#/definitions/uint32-array
> +              description:
> +                 The channels included on this port. Format is channel start
> +                 number and how many channels on this port.
> +
> +            intel,port-burst:
> +              $ref: /schemas/types.yaml#/definitions/uint32
> +              description:
> +                 Specify the DMA port burst size, the valid value will be
> +                 2, 4, 8. Default is 2 for data path dma.
> +
> +            intel,port-txwgt:
> +              $ref: /schemas/types.yaml#/definitions/uint32
> +              description:
> +                 Specify the port transmit weight for QoS purpose. The valid
> +                 value is 1~7. Default value is 1.
> +
> +            intel,port-endian:
> +              $ref: /schemas/types.yaml#/definitions/uint32
> +              description:
> +                 Specify the DMA port endiannes conversion due to SoC endianness difference.
> +
> +          required:
> +            - reg
> +            - intel,port-name
> +            - intel,port-chans
> +
> +
> + dma-channels:
> +    type: object
> +    description:
> +       This sub-node must contain a sub-node for each DMA channel.
> +    properties:
> +      '#address-cells':
> +        const: 1
> +      '#size-cells':
> +        const: 0
> +
> +    patternProperties:
> +      "^dma-channels@[0-9]+$":
> +          type: object
> +
> +          properties:
> +            reg:
> +              items:
> +                - enum: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15]
> +              description:
> +                 Which channel this node refers to.
> +
> +            intel,chan-desc_num:
> +              $ref: /schemas/types.yaml#/definitions/uint32
> +              description:
> +                 Per channel maximum descriptor number. The max value is 255.
> +
> +            intel,chan-pkt_sz:
> +              $ref: /schemas/types.yaml#/definitions/uint32
> +              description:
> +                 Channel buffer packet size. It must be power of 2.
> +                 The maximum size is 4096.
> +
> +            intel,chan-desc-rx-nonpost:
> +              type: boolean
> +              description:
> +                 Write non-posted type for DMA RX last data beat of every descriptor.
> +
> +            intel,chan-data-endian:
> +              $ref: /schemas/types.yaml#/definitions/uint32
> +              description:
> +                 Per channel data endianness configuration according to SoC requirement.
> +
> +            intel,chan-desc-endian:
> +              $ref: /schemas/types.yaml#/definitions/uint32
> +              description:
> +                 Per channel descriptor endianness configuration according to SoC requirement.
> +
> +            intel,chan-data-endian-en:
> +              type: boolean
> +              description:
> +                 Per channel data endianness enabled.
> +
> +            intel,chan-desc-endian-en:
> +              type: boolean
> +              description:
> +                 Per channel descriptor endianness enabled.
> +
> +            intel,chan-byte-offset:
> +              $ref: /schemas/types.yaml#/definitions/uint32
> +              description:
> +                 Per channel byte offset(0~128).
> +
> +            intel,chan-hdr-mode:
> +              $ref: /schemas/types.yaml#/definitions/uint32-array
> +              description:
> +                 The first parameter is header mode size, the second
> +                 parameter is checksum enable or disable. If enabled,
> +                 header mode size is ignored. If disabled, header mode
> +                 size must be provided.
> +
> +            intel,chan-non-arb-cnt:
> +              $ref: /schemas/types.yaml#/definitions/uint32
> +              description:
> +                 Per channel non arbitration counter while polling
> +
> +            intel,chan-arb-cnt:
> +              $ref: /schemas/types.yaml#/definitions/uint32
> +              description:
> +                 Per channel arbitration counter while polling.
> +                 arb_cnt must be greater than non_arb_cnt
> +
> +            intel,chan-pkt-drop:
> +              type: boolean
> +              description:
> +                 Channel packet drop enabled or disabled.
> +
> +            intel,chan-hw-desc:
> +              $ref: /schemas/types.yaml#/definitions/uint32-array
> +              description:
> +                 Per channel dma hardware descriptor configuration.
> +                 The first parameter is descriptor physical address and the
> +                 second parameter hardware descriptor number.
> +
> +          required:
> +            - reg
> +
> +required:
> + - compatible
> + - reg
> + - '#dma-cells'
> +
> +examples:
> + - |
> +   dma0: dma@e0e00000 {
> +     compatible = "intel,lgm-cdma";
> +     reg = <0xe0e00000 0x1000>;
> +     #dma-cells = <1>;
> +     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;
> +     dma-ports {
> +       #address-cells = <1>;
> +       #size-cells = <0>;
> +
> +       dma-ports@0 {
> +           reg = <0>;
> +           intel,port-name = "SPI0";
> +           intel,port-chans = <0 2>;
> +           intel,port-burst = <2>;
> +           intel,port-txwgt = <1>;
> +       };
> +       dma-ports@1 {
> +           reg = <1>;
> +           intel,port-name = "SPI1";
> +           intel,port-chans = <2 2>;
> +           intel,port-burst = <2>;
> +           intel,port-txwgt = <1>;
> +       };
> +       dma-ports@2 {
> +           reg = <2>;
> +           intel,port-name = "SPI2";
> +           intel,port-chans = <4 2>;
> +           intel,port-burst = <2>;
> +           intel,port-txwgt = <1>;
> +       };
> +       dma-ports@3 {
> +           reg = <3>;
> +           intel,port-name = "SPI3";
> +           intel,port-chans = <6 2>;
> +           intel,port-burst = <2>;
> +           intel,port-endian = <0>;
> +           intel,port-txwgt = <1>;
> +       };
> +       dma-ports@4 {
> +           reg = <4>;
> +           intel,port-name = "HSNAND";
> +           intel,port-chans = <8 2>;
> +           intel,port-burst = <8>;
> +           intel,port-txwgt = <1>;
> +       };
> +       dma-ports@5 {
> +           reg = <5>;
> +           intel,port-name = "PCM";
> +           intel,port-chans = <10 6>;
> +           intel,port-burst = <8>;
> +           intel,port-txwgt = <1>;
> +       };
> +     };
> +     dma-channels {
> +       #address-cells = <1>;
> +       #size-cells = <0>;
> +
> +       dma-channels@0 {
> +           reg = <0>;
> +           intel,chan-desc_num = <1>;
> +       };
> +       dma-channels@1 {
> +           reg = <1>;
> +           intel,chan-desc_num = <1>;
> +       };
> +       dma-channels@2 {
> +           reg = <2>;
> +           intel,chan-desc_num = <1>;
> +       };
> +       dma-channels@3 {
> +           reg = <3>;
> +           intel,chan-desc_num = <1>;
> +       };
> +       dma-channels@4 {
> +           reg = <4>;
> +           intel,chan-desc_num = <1>;
> +       };
> +       dma-channels@5 {
> +           reg = <5>;
> +           intel,chan-desc_num = <1>;
> +       };
> +       dma-channels@6 {
> +           reg = <6>;
> +           intel,chan-desc_num = <1>;
> +       };
> +       dma-channels@7 {
> +           reg = <7>;
> +           intel,chan-desc_num = <1>;
> +       };
> +       dma-channels@8 {
> +           reg = <8>;
> +       };
> +       dma-channels@9 {
> +           reg = <9>;
> +       };
> +       dma-channels@10 {
> +           reg = <10>;
> +       };
> +       dma-channels@11 {
> +           reg = <11>;
> +       };
> +       dma-channels@12 {
> +           reg = <12>;
> +       };
> +       dma-channels@13 {
> +           reg = <13>;
> +       };
> +       dma-channels@14 {
> +           reg = <14>;
> +       };
> +       dma-channels@15 {
> +           reg = <15>;
> +       };
> +     };
> +   };
> + - |
> +   dma3: dma@ec800000 {
> +     compatible = "intel,lgm-dma3";
> +     reg = <0xec800000 0x1000>;
> +     clocks = <&cgu0 71>;
> +     resets = <&rcu0 0x10 9>;
> +     #dma-cells = <1>;
> +     intel,dma-burst = <32>;
> +     intel,dma-polling-cnt = <16>;
> +     intel,dma-desc-in-sram;
> +     intel,dma-orrc = <16>;
> +     intel,dma-byte-en;
> +     intel,dma-txendi = <0>;
> +     intel,dma-rxendi = <0>;
> +     intel,dma-dburst-wr;
> +     dma-channels {
> +         #address-cells = <1>;
> +         #size-cells = <0>;
> +
> +         dma-channels@12 {
> +             reg = <12>;
> +             intel,chan-pkt_sz = <4096>;
> +             intel,chan-desc-rx-nonpost;
> +             intel,chan-data-endian = <0>;
> +             intel,chan-desc-endian = <0>;
> +             intel,chan-data-endian-en;
> +             intel,chan-desc-endian-en;
> +             intel,chan-byte-offset = <0>;
> +             intel,chan-hdr-mode = <128 0>;
> +             intel,chan-non-arb-cnt = <0>;
> +             intel,chan-arb-cnt = <0>;
> +             intel,chan-hw-desc = <0x20000000 8>;
> +         };
> +         dma-channels@13 {
> +             reg = <13>;
> +             intel,chan-pkt-drop;
> +             intel,chan-pkt_sz = <4096>;
> +             intel,chan-data-endian = <0>;
> +             intel,chan-desc-endian = <0>;
> +             intel,chan-data-endian-en;
> +             intel,chan-desc-endian-en;
> +             intel,chan-byte-offset = <0>;
> +             intel,chan-hdr-mode = <128 0>;
> +             intel,chan-non-arb-cnt = <0>;
> +             intel,chan-arb-cnt = <0>;
> +         };
> +     };
> +   };
> --
> 2.11.0