linux-kernel - Re: [PATCH v3 1/3] dt-bindings: display: ti,am65x-dss: Add am62p dss compatible

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Message-ID: <20260108-expert-whippet-of-downpour-ba277f@quoll>
Date: Thu, 8 Jan 2026 09:51:08 +0100
From: Krzysztof Kozlowski <krzk@...nel.org>
To: Swamil Jain <s-jain1@...com>
Cc: jyri.sarha@....fi, tomi.valkeinen@...asonboard.com, airlied@...il.com, 
	simona@...ll.ch, maarten.lankhorst@...ux.intel.com, mripard@...nel.org, 
	tzimmermann@...e.de, robh@...nel.org, krzk+dt@...nel.org, conor+dt@...nel.org, 
	aradhya.bhatia@...ux.dev, dri-devel@...ts.freedesktop.org, devicetree@...r.kernel.org, 
	linux-kernel@...r.kernel.org, devarsht@...com, praneeth@...com, h-shenoy@...com, 
	u-kumar1@...com
Subject: Re: [PATCH v3 1/3] dt-bindings: display: ti,am65x-dss: Add am62p dss
 compatible

On Wed, Jan 07, 2026 at 11:15:23PM +0530, Swamil Jain wrote:
> TI's AM62P SoC contains two instances of the TI Keystone Display
> SubSystem (DSS), each with two video ports and two video planes. These
> instances support up to three independent video streams through OLDI,
> DPI, and DSI interfaces.
> 
> DSS0 (first instance) supports:
>  - Two OLDI transmitters on video port 1, configurable in dual-link or
>    single-link mode.
>  - DPI output on video port 2.
> 
> DSS1 (second instance) supports:
>  - One OLDI transmitter on video port 1 (single-link mode only).
>  - DSI controller output on video port 2.
> 
> The two OLDI transmitters can be configured in clone mode to drive a
> pair of identical OLDI single-link displays. DPI outputs from
> DSS0 VP2, DSS1 VP1, and DSS1 VP2 are multiplexed, allowing only one
> DPI output at a time.
> 
> Add the compatible string "ti,am62p-dss" and update related
> description accordingly.
> 
> AM62P has different power domains for DSS and OLDI compared to other
> Keystone SoCs. Therefore, add 'minItems' and set to 1 and 'maxItems'
> field in the power-domains property to 3 for the "ti,am62p-dss"
> compatible entry to reflect this hardware difference.

Last sentence is redundant. You are again explain repeating the diff
which is pointless, but did not explain WHY you think 2 power domains is
correct.

> 
> Signed-off-by: Swamil Jain <s-jain1@...com>
> ---
>  .../bindings/display/ti/ti,am65x-dss.yaml     | 33 ++++++++++++++++++-
>  1 file changed, 32 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/devicetree/bindings/display/ti/ti,am65x-dss.yaml b/Documentation/devicetree/bindings/display/ti/ti,am65x-dss.yaml
> index 38fcee91211e..e74e710934fc 100644
> --- a/Documentation/devicetree/bindings/display/ti/ti,am65x-dss.yaml
> +++ b/Documentation/devicetree/bindings/display/ti/ti,am65x-dss.yaml
> @@ -24,6 +24,19 @@ description: |
>    DPI signals are also routed internally to DSI Tx controller present within the
>    SoC. Due to clocking limitations only one of the interface i.e. either DSI or
>    DPI can be used at once.
> +  The AM62P has two instances of TI Keystone Display SubSystem, each with two
> +  video ports and two video planes. These instances can support up to 3
> +  independent video streams through OLDI, DPI, and DSI interfaces.
> +  DSS0 (first instance) supports:
> +    - Two OLDI TXes on video port 1, configurable in dual-link or
> +      single link clone mode
> +    - DPI output on video port 2
> +  DSS1 (second instance) supports:
> +    - One OLDI TX on video port 1 (single-link mode only)
> +    - DSI controller output on video port 2
> +  The two OLDI TXes can be configured in clone mode to drive a pair of
> +  identical OLDI single-link displays. DPI outputs from DSS0 VP2, DSS1 VP1,
> +  and DSS1 VP2 are muxed, allowing only one DPI output at a time.
>  
>  properties:
>    compatible:
> @@ -31,6 +44,7 @@ properties:
>        - ti,am625-dss
>        - ti,am62a7-dss
>        - ti,am62l-dss
> +      - ti,am62p-dss
>        - ti,am65x-dss
>  
>    reg:
> @@ -81,7 +95,8 @@ properties:
>      maxItems: 1
>  
>    power-domains:
> -    maxItems: 1
> +    minItems: 1
> +    maxItems: 3
>      description: phandle to the associated power domain
>  
>    dma-coherent: true
> @@ -196,6 +211,22 @@ allOf:
>                properties:
>                  endpoint@1: false
>  
> +  - if:
> +      properties:
> +        compatible:
> +          contains:
> +            const: ti,am62p-dss
> +    then:
> +      properties:
> +        power-domains:
> +          minItems: 1
> +          maxItems: 3

This is still not constrained enough. You need to define the items
instead. I still do not understand why number of power domains is
flexible.

> +    else:
> +      properties:
> +        power-domains:
> +          minItems: 1

You can drop this one.

> +          maxItems: 1
> +
>  required:
>    - compatible
>    - reg