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Subject: Re: [PATCH v9 1/2] dt-bindings: dma: Add bindings for Intel LGM SoC
To:     Vinod Koul <vkoul@kernel.org>
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
References: <cover.1605158930.git.mallikarjunax.reddy@linux.intel.com>
 <bfe586ac62080d14759bda22ebf1de1a1fa9c09d.1605158930.git.mallikarjunax.reddy@linux.intel.com>
 <20201118155552.GV50232@vkoul-mobl>
 <44fba7c3-37a9-7168-3c19-eeb5068b7063@linux.intel.com>
 <20201121121917.GC8403@vkoul-mobl>
 <f9eedf31-0452-590b-061a-2946594bc9ea@linux.intel.com>
 <20201124172309.GU8403@vkoul-mobl>
From:   "Reddy, MallikarjunaX" <mallikarjunax.reddy@linux.intel.com>
Message-ID: <9fe5ddaf-a2b5-b788-9d82-ed5eab310b81@linux.intel.com>
Date:   Wed, 25 Nov 2020 18:39:44 +0800
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Hi Vinod,

Thanks for your review comments, My comments inline.

On 11/25/2020 1:23 AM, Vinod Koul wrote:
> On 24-11-20, 00:30, Reddy, MallikarjunaX wrote:
>> Hi Vinod,
>>
>> Thanks for your valuable review. My comments inline.
>>
>> On 11/21/2020 8:19 PM, Vinod Koul wrote:
>>> On 20-11-20, 19:30, Reddy, MallikarjunaX wrote:
>>>> Hi Vinod,
>>>> Thanks for the review. My comments inline.
>>>>
>>>> On 11/18/2020 11:55 PM, Vinod Koul wrote:
>>>>> 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
>>>> Ok, Thanks.
>>>>>> +      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..?
>>>> when dma-byte-en = 0 (disabled) DMA write will be in terms of burst length,
>>>> dma-byte-en = 1 (enabled) write will be in terms of Dwords.
>>>>
>>>> Byte enable = 0 (Disabled) means that DMA write will be based on the burst
>>>> length, even if it only transmits one byte.
>>>> Byte enable = 1(enabled) means that DMA write will be based on the number of
>>>> Dwords, instead of the whole burst.
>>> Sounds like a hw property or is this configurable to engine..?
>> Yes its hw property. Not configurable to engine.
>>>>>> +
>>>>>> +  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?
>>>> This is DMA controller capability. It can be decided from driver also. i
>>>> will change accordingly.
>>>>>> +
>>>>>> +  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..?
>>>> A register bit will be used to enable/disable the ORR feature.
>>>>
>>>> Outstanding Read Capability introduce CMD FIFO to support up to 16
>>>> outstanding reads for different packet in same channel.
>>>>
>>>> For large packets up to 16 OR can be issued, the number of OR is
>>>> configurable.
>>> How will configure this and when..?
>> This is DMA (ver > DMA_VER22) hw capability and is configured from device
>> tree.
>>
>> If this property is not present or count is zero means orrc capability is
>> disabled.
>> If orrc count is 4 <= orr_cnt < 16 then write the enable bit and value to
>> corresponding register.
>>
>> Ex:
>>          if (d->orrc > 0 && d->orrc <= DMA_ORRC_MAX_CNT)
>>                  val = DMA_ORRC_EN | FIELD_PREP(DMA_ORRC_ORRCNT, d->orrc);
>>
>>          ldma_update_bits(d, mask, val, DMA_ORRC);
>>
>> This hw capability supports dma instances ver > DMA_VER22.
> Sounds like this can be coded in driver and used based on compatible?
Yes, we can do that. I will update in the next patch.
>