Re: [PATCH v4 1/3] media: dt-bindings: rockchip,vdec: Add alternative reg-names order for RK35{76,88}

[Conor Dooley <conor@kernel.org>]

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On Thu, Feb 26, 2026 at 12:46:53PM +0200, Cristian Ciocaltea wrote:
> With the introduction of the RK3588 SoC, and RK3576 afterwards, two more
> register blocks have been provided for the video decoder unit.
> 
> However, the binding does not properly describe the new hardware layout,
> as it breaks the convention expecting the unit address to indicate the
> start of the first register range, i.e. 'function' block is listed
> before 'link' instead of the opposite.

I don't understand this commit message or rationale for an ABI break.
Changing the unit address seems like a "free" fix to your problem,
especially when reg-names is not a required property that you can rely
on. Actually, there may be a bug in the driver - it expects reg-names
for rk3576-vdec and rk3588-vdec but the binding doesn't mandate their
presence for those devices.

Deprecating the order also makes little sense to me, given that some of
these devices only have one reg entry, which as far as I can tell from
looking at the driver *is* the "function" region, so it can never be
entirely deprecated.

Confused,
Conor.

> 
> Since the binding changes have been already released and a fix would
> bring up an ABI break, mark the current 'reg-names' ordering as
> deprecated and introduce an alternative 'link,function,cache' listing
> which follows the address-based ordering according to the TRM.
> 
> Additionally, drop the 'reg' description items as the order is not fixed
> anymore, while the information they offer is not very relevant anyway.
> 
> Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
> ---
>  .../devicetree/bindings/media/rockchip,vdec.yaml     | 20 ++++++++++++--------
>  1 file changed, 12 insertions(+), 8 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/media/rockchip,vdec.yaml b/Documentation/devicetree/bindings/media/rockchip,vdec.yaml
> index 809fda45b3bd..c513b68d2c72 100644
> --- a/Documentation/devicetree/bindings/media/rockchip,vdec.yaml
> +++ b/Documentation/devicetree/bindings/media/rockchip,vdec.yaml
> @@ -28,16 +28,20 @@ properties:
>  
>    reg:
>      minItems: 1
> -    items:
> -      - description: The function configuration registers base
> -      - description: The link table configuration registers base
> -      - description: The cache configuration registers base
> +    maxItems: 3
>  
>    reg-names:
> -    items:
> -      - const: function
> -      - const: link
> -      - const: cache
> +    oneOf:
> +      - items:
> +          - const: link
> +          - const: function
> +          - const: cache
> +      - items:
> +          - const: function
> +          - const: link
> +          - const: cache
> +        deprecated: true
> +        description: Use link,function,cache block order instead.
>  
>    interrupts:
>      maxItems: 1
> 
> -- 
> 2.52.0
> 

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