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Date:   Mon, 13 Jul 2020 11:22:11 -0600
From:   Rob Herring <robh@kernel.org>
To:     "Reddy, MallikarjunaX" <mallikarjunax.reddy@linux.intel.com>
Cc:     "Langer, Thomas" <thomas.langer@intel.com>,
        "dmaengine@vger.kernel.org" <dmaengine@vger.kernel.org>,
        "vkoul@kernel.org" <vkoul@kernel.org>,
        "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "Shevchenko, Andriy" <andriy.shevchenko@intel.com>,
        "chuanhua.lei@linux.intel.com" <chuanhua.lei@linux.intel.com>,
        "Kim, Cheol Yong" <cheol.yong.kim@intel.com>,
        "Wu, Qiming" <qi-ming.wu@intel.com>,
        "malliamireddy009@gmail.com" <malliamireddy009@gmail.com>,
        mallikarjunax.reddy@intel.com
Subject: Re: [PATCH v4 1/2] dt-bindings: dma: Add bindings for intel LGM SOC
Message-ID: <20200713172211.GA391669@bogus>
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On Mon, Jul 13, 2020 at 11:39:49AM +0800, Reddy, MallikarjunaX wrote:
> Hi Thomas,
> 
> Thanks for the review. My comments inline.
> 
> On 7/9/2020 3:54 PM, Langer, Thomas wrote:
> > 
> > > -----Original Message-----
> > > From: devicetree-owner@vger.kernel.org <devicetree-
> > > owner@vger.kernel.org> On Behalf Of Amireddy Mallikarjuna reddy
> > > Sent: Donnerstag, 9. Juli 2020 08:01
> > > To: dmaengine@vger.kernel.org; vkoul@kernel.org;
> > > devicetree@vger.kernel.org; robh+dt@kernel.org
> > > Cc: linux-kernel@vger.kernel.org; Shevchenko, Andriy
> > > <andriy.shevchenko@intel.com>; chuanhua.lei@linux.intel.com; Kim, Cheol
> > > Yong <cheol.yong.kim@intel.com>; Wu, Qiming <qi-ming.wu@intel.com>;
> > > malliamireddy009@gmail.com; Amireddy Mallikarjuna reddy
> > > <mallikarjunax.reddy@linux.intel.com>
> > > Subject: [PATCH v4 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@linux.intel.com>
> > > ---
> > > v1:
> > > - Initial version.
> > > 
> > > v2:
> > > - Fix bot errors.
> > > 
> > > v3:
> > > - No change.
> > > 
> > > v4:
> > > - Address Thomas langer comments
> > Please read my comments again and then respond about the topics you ignored.
> > I added some hints below again.
> > 
> > Thanks.
> > 
> > > ---
> > >   .../devicetree/bindings/dma/intel,ldma.yaml        | 416
> > > +++++++++++++++++++++
> > >   1 file changed, 416 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..7f666b9812e4
> > > --- /dev/null
> > > +++ b/Documentation/devicetree/bindings/dma/intel,ldma.yaml
> > > @@ -0,0 +1,416 @@
> > > +# 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
> > > +
> > > +properties:
> > > + $nodename:
> > > +   pattern: "^dma(@.*)?$"
> > Please explain the difference to the common dma binding.
> No difference. we can use "^dma-controller(@.*)?$" as in the common binding.
> Its My bad. I missed the changes to include in this patch. Surely update in
> the upcoming patch.
> > 
> > > +
> > > + "#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
> > Please explain why you need so many different compatible strings.
> This hw dma has 7 DMA instances.
> Some for datapath, some for memcpy? and some for TOE.
> Some for TX only, some for RX only, and some for TX/RX(memcpy and ToE).
> 
> dma TX/RX type we considered as driver specific data of each instance and
> used different compatible strings for each instance.
> And also idea is in future if any driver specific data of any particular
> instance we can handle.
> 
> Here if dma name and type(tx or rx) will be accepted as devicetree
> attributes then we can move .name = "toe_dma31", & .type = DMA_TYPE_MCPY
> to devicetree. So that the compatible strings can be limited to two.
> intel,lgm-cdma & intel,lgm-hdma .

Different compatibles are okay if the instances are different and we 
don't have properties to describe the differences.

For some of what you have in this binding, I think it should be part of 
the consumer cells.

> 
> please suggest us the better proposal.
> > 
> > > +
> > > + 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:

What's the difference with 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-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-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.

What's a 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.
> > > +
> > > +            intel,name:
> > > +              $ref: /schemas/types.yaml#definitions/string-array
> > > +              description:
> > > +                 Port name of each DMA port.

Why do you need this?

> > > +
> > > +            intel,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.

We already have standard properties for defining channels.

> > > +
> > > +            intel,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.

This would normally be in the consumer cells.

> > > +
> > > +            intel,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,endian:
> > > +              $ref: /schemas/types.yaml#/definitions/uint32
> > > +              description:
> > > +                 Specify the DMA port endiannes conversion due to SoC
> > > endianness difference.
> > > +
> > > +          required:
> > > +            - reg
> > > +            - intel,name
> > > +            - intel,chans
> > > +
> > > +
> > > + dma-channels:
> > > +    type: object
> > > +    description:
> > > +       This sub-node must contain a sub-node for each DMA channel.
> > > +    properties:
> > > +      '#address-cells':
> > > +        const: 1
> > > +      '#size-cells':
> > > +        const: 0
> > > +
> > > +    patternProperties:
> > > +      "^dma-channels@[0-9]+$":
> > > +          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,desc_num:
> > > +              $ref: /schemas/types.yaml#/definitions/uint32
> > > +              description:
> > > +                 Per channel maximum descriptor number. The max value
> > > is 255.
> > > +
> > > +            intel,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,desc-rx-nonpost:
> > > +              type: boolean
> > > +              description:
> > > +                 Write non-posted type for DMA RX last data beat of
> > > every descriptor.
> > > +
> > > +            intel,data-endian:
> > > +              $ref: /schemas/types.yaml#/definitions/uint32
> > > +              description:
> > > +                 Per channel data endianness configuration according to
> > > SoC requirement.
> > > +
> > > +            intel,desc-endian:
> > > +              $ref: /schemas/types.yaml#/definitions/uint32
> > > +              description:
> > > +                 Per channel descriptor endianness configuration
> > > according to SoC requirement.
> > > +
> > > +            intel,data-endian-en:
> > > +              type: boolean
> > > +              description:
> > > +                 Per channel data endianness enabled.
> > > +
> > > +            intel,desc-endian-en:
> > > +              type: boolean
> > > +              description:
> > > +                 Per channel descriptor endianness enabled.
> > > +
> > > +            intel,byte-offset:
> > > +              $ref: /schemas/types.yaml#/definitions/uint32
> > > +              description:
> > > +                 Per channel byte offset(0~128).
> > > +
> > > +            intel,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,non-arb-cnt:
> > > +              $ref: /schemas/types.yaml#/definitions/uint32
> > > +              description:
> > > +                 Per channel non arbitration counter while polling
> > > +
> > > +            intel,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,pkt-drop:
> > > +              type: boolean
> > > +              description:
> > > +                 Channel packet drop enabled or disabled.
> > > +
> > > +            intel,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.

All/most of these seem like client/consumer settings.

> > > +
> > > +          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,name = "SPI0";
> > > +           intel,chans = <0 2>;
> > > +           intel,burst = <2>;
> > > +           intel,txwgt = <1>;

Yeah, based on the names, it definitely seems like these belong as cells 
in 'dmas' properties.

> > > +       };
> > > +       dma-ports@1 {
> > > +           reg = <1>;
> > > +           intel,name = "SPI1";
> > > +           intel,chans = <2 2>;
> > > +           intel,burst = <2>;
> > > +           intel,txwgt = <1>;
> > > +       };
> > > +       dma-ports@2 {
> > > +           reg = <2>;
> > > +           intel,name = "SPI2";
> > > +           intel,chans = <4 2>;
> > > +           intel,burst = <2>;
> > > +           intel,txwgt = <1>;
> > > +       };
> > > +       dma-ports@3 {
> > > +           reg = <3>;
> > > +           intel,name = "SPI3";
> > > +           intel,chans = <6 2>;
> > > +           intel,burst = <2>;
> > > +           intel,endian = <0>;
> > > +           intel,txwgt = <1>;
> > > +       };
> > > +       dma-ports@4 {
> > > +           reg = <4>;
> > > +           intel,name = "HSNAND";
> > > +           intel,chans = <8 2>;
> > > +           intel,burst = <8>;
> > > +           intel,txwgt = <1>;
> > > +       };
> > > +       dma-ports@5 {
> > > +           reg = <5>;
> > > +           intel,name = "PCM";
> > > +           intel,chans = <10 6>;
> > > +           intel,burst = <8>;
> > > +           intel,txwgt = <1>;
> > > +       };
> > > +     };
> > > +     dma-channels {
> > > +       #address-cells = <1>;
> > > +       #size-cells = <0>;
> > > +
> > > +       dma-channels@0 {
> > > +           reg = <0>;
> > > +           intel,desc_num = <1>;
> > > +       };
> > > +       dma-channels@1 {
> > > +           reg = <1>;
> > > +           intel,desc_num = <1>;
> > > +       };
> > > +       dma-channels@2 {
> > > +           reg = <2>;
> > > +           intel,desc_num = <1>;
> > > +       };
> > > +       dma-channels@3 {
> > > +           reg = <3>;
> > > +           intel,desc_num = <1>;
> > > +       };
> > > +       dma-channels@4 {
> > > +           reg = <4>;
> > > +           intel,desc_num = <1>;
> > > +       };
> > > +       dma-channels@5 {
> > > +           reg = <5>;
> > > +           intel,desc_num = <1>;
> > > +       };
> > > +       dma-channels@6 {
> > > +           reg = <6>;
> > > +           intel,desc_num = <1>;
> > > +       };
> > > +       dma-channels@7 {
> > > +           reg = <7>;
> > > +           intel,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-dburst-wr;
> > > +     dma-channels {
> > > +         #address-cells = <1>;
> > > +         #size-cells = <0>;
> > > +
> > > +         dma-channels@12 {
> > > +             reg = <12>;
> > > +             intel,pkt_sz = <4096>;
> > > +             intel,desc-rx-nonpost;
> > > +             intel,data-endian = <0>;
> > > +             intel,desc-endian = <0>;
> > > +             intel,data-endian-en;
> > > +             intel,desc-endian-en;
> > > +             intel,byte-offset = <0>;
> > > +             intel,hdr-mode = <128 0>;
> > > +             intel,non-arb-cnt = <0>;
> > > +             intel,arb-cnt = <0>;
> > > +             intel,hw-desc = <0x20000000 8>;
> > > +         };
> > > +         dma-channels@13 {
> > > +             reg = <13>;
> > > +             intel,pkt-drop;
> > > +             intel,pkt_sz = <4096>;
> > > +             intel,data-endian = <0>;
> > > +             intel,desc-endian = <0>;
> > > +             intel,data-endian-en;
> > > +             intel,desc-endian-en;
> > > +             intel,byte-offset = <0>;
> > > +             intel,hdr-mode = <128 0>;
> > > +             intel,non-arb-cnt = <0>;
> > > +             intel,arb-cnt = <0>;
> > > +         };
> > > +     };
> > > +   };
> > > --
> > > 2.11.0