Re: [PATCH v2 1/3] dt-bindings: lgm-dma: Added intel,dma-sw-desc property.

[Krzysztof Kozlowski <krzk@kernel.org>]

On 15/08/2025 12:06, Yi xin Zhu wrote:
> Hi Krzysztof,
> On 15/08/2025 16:32, Krzysztof wrote:
>>
>>
>> And how is it not a OS policy? Bring reasoning and arguments, otherwise I
>> cannot help you. Your reply above has zero hardware-related arguments, zero
>> facts, zero hardware description.
>>
>> Best regards,
>> Krzysztof
> 
> Let me first describe the DMA hardware capability.  The DMA IP is designed with two control paths.
> 1. Hardware descriptor mode.  The DMA can be connected to another HW component that provides
> Descriptors to DMA to automate DMA transfers.
> 2. Software descriptor mode.  The DMA IP also has interface to CPU via registers to allow CPU to
> manage the DMA transfers.
> 
> Which mode DMA works in depends on SoC level configuration.  In the SoC, it could be some

What is a "SoC level configuration"?

From your explanation 1+2 it feels like consumer chooses it. Where is a
full DTS showing all this?


> of the DMA instances work in hardware descriptor mode while other DMA instances work in
> software descriptor mode or all in HW/SW mode.
> 

Best regards,
Krzysztof