Re: [PATCH v3, 03/10] dt-bindings: media: mtk-vcodec: Adds encoder cores dt-bindings for mt8195

[Rob Herring <robh@kernel.org>]

On Sat, Mar 26, 2022 at 10:00:55AM +0800, Irui Wang wrote:
> Dear Rob,
> 
> Thanks for your review and comments.
> 
> On Fri, 2022-03-25 at 15:57 -0500, Rob Herring wrote:
> > On Thu, Mar 17, 2022 at 04:22:23PM +0800, Irui Wang wrote:
> > > Adds encoder cores dt-bindings for mt8195.
> > 
> > Why?
> mt8195 has two h264 encoder cores and we want to enable both of them.
> the original encoder bindings file is for single core which may can not
> handle it, so we new a core dt-bindings. We will think about it again
> about this dt-bindings.
> > 
> > > 
> > > Signed-off-by: Irui Wang <irui.wang@mediatek.com>
> > > ---
> > >  .../media/mediatek,vcodec-encoder-core.yaml   | 181
> > > ++++++++++++++++++
> > >  .../media/mediatek,vcodec-encoder.yaml        |   1 -
> > >  2 files changed, 181 insertions(+), 1 deletion(-)
> > >  create mode 100644
> > > Documentation/devicetree/bindings/media/mediatek,vcodec-encoder-
> > > core.yaml
> > > 
> > > diff --git
> > > a/Documentation/devicetree/bindings/media/mediatek,vcodec-encoder-
> > > core.yaml
> > > b/Documentation/devicetree/bindings/media/mediatek,vcodec-encoder-
> > > core.yaml
> > > new file mode 100644
> > > index 000000000000..fcfb48900c76
> > > --- /dev/null
> > > +++ b/Documentation/devicetree/bindings/media/mediatek,vcodec-
> > > encoder-core.yaml
> > > @@ -0,0 +1,181 @@
> > > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > > +
> > > +%YAML 1.2
> > > +---
> > > +$id: "
> > > http://devicetree.org/schemas/media/mediatek,vcodec-encoder-core.yaml#
> > > "
> > > +$schema: "http://devicetree.org/meta-schemas/core.yaml#"
> > > +
> > > +title: Mediatek Video Encoder Accelerator With Multi Core
> > > +
> > > +maintainers:
> > > +  - Irui Wang <irui.wang@mediatek.com>
> > > +
> > > +description: |
> > > +  Mediatek Video Encode is the video encode hardware present in
> > > Mediatek
> > > +  SoCs which supports high resolution encoding functionalities.
> > > Required
> > > +  parent and child device node.
> > > +
> > > +properties:
> > > +  compatible:
> > > +    items:
> > > +      - enum:
> > > +          - mediatek,mt8195-vcodec-enc
> > > +
> > > +  mediatek,scp:
> > > +    $ref: /schemas/types.yaml#/definitions/phandle
> > > +    description: |
> > > +      The node of system control processor (SCP), using
> > > +      the remoteproc & rpmsg framework.
> > > +
> > > +  mediatek,venc-multi-core:
> > > +    type: boolean
> > > +    description: |
> > > +      Indicates whether the encoder has multiple cores or not.
> > 
> > Isn't this implied by how many child nodes you have?
> It implies that we have child nodes, distinguish with single core,  

Just check if you have a child node or not.


> > > +  iommus:
> > > +    minItems: 1
> > > +    maxItems: 32
> > 
> > You really have up to 32 IOMMUs?
> Currently, totally 27 IOMMUs and used 9 of them.
> > 
> > > +    description: |
> > > +      List of the hardware port in respective IOMMU block for
> > > current Socs.
> > > +      Refer to bindings/iommu/mediatek,iommu.yaml.
> > > +
> > > +  dma-ranges:
> > > +    maxItems: 1
> > > +    description: |
> > > +      Describes the physical address space of IOMMU maps to
> > > memory.
> > > +
> > > +  "#address-cells":
> > > +    const: 2
> > > +
> > > +  "#size-cells":
> > > +    const: 2
> > > +
> > > +  ranges: true
> > > +
> > > +# Required child node:
> > > +patternProperties:
> > > +  "^venc-core@[0-9a-f]+$":
> > > +    type: object
> > > +    description: |
> > > +      The video encoder core device node which should be added as
> > > subnodes to
> > > +      the main venc node.
> > > +
> > > +    properties:
> > > +      compatible:
> > > +        items:
> > > +         - const: mediatek,mtk-venc-core
> > > +
> > > +      reg:
> > > +        maxItems: 1
> > > +
> > > +      mediatek,core-id:
> > > +        $ref: /schemas/types.yaml#/definitions/uint32
> > > +        description: |
> > > +          Current encoder core id.
> > 
> > What is this for and what does its value correspond to in the h/w.
> > We 
> > generally don't do made up indices in DT.
> It's for encoder core id, core@1a020000 must be core-0, core@1b020000
> must be core-1, we add this property in each child node, so we can 
> get core-id in drivers. If it can't ref "uint32" types yaml, would 
> you mind giving some more suggestions ?

I still don't understand why it is needed. What is 'core-0'?

Is there some functional difference between the cores? If so, describe 
that difference.

Rob