linux-kernel - Re: [PATCH v3 03/10] dt-bindings: display: rockchip,dw-mipi-dsi: Drop address/size cells

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Message-Id: <DB6T5PTAYT5J.3OYZYN2OZ01EC@cknow.org>
Date: Tue, 08 Jul 2025 18:18:32 +0200
From: "Diederik de Haas" <didi.debian@...ow.org>
To: "Rob Herring" <robh@...nel.org>
Cc: "Krzysztof Kozlowski" <krzk+dt@...nel.org>, "Conor Dooley"
 <conor+dt@...nel.org>, "Heiko Stuebner" <heiko@...ech.de>, "Dragan Simic"
 <dsimic@...jaro.org>, "Quentin Schulz" <quentin.schulz@...rry.de>, "Johan
 Jonker" <jbx6244@...il.com>, <devicetree@...r.kernel.org>,
 <linux-arm-kernel@...ts.infradead.org>,
 <linux-rockchip@...ts.infradead.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 03/10] dt-bindings: display: rockchip,dw-mipi-dsi:
 Drop address/size cells

On Tue Jul 8, 2025 at 5:47 PM CEST, Rob Herring wrote:
> On Sun, Jun 29, 2025 at 02:34:44PM +0200, Diederik de Haas wrote:
>> When the dw-mipi-dsi binding was initially added in commit
>> a20d86e7f964 ("Documentation: dt-bindings: Add bindings for rk3288 DW MIPI DSI driver")
>> the #address-cells and #size-cells were added as required properties.
>> 
>> When the binding was converted to yaml format in commit
>> 0dac2102cf6b ("dt-bindings: display: rockchip: convert dw_mipi_dsi_rockchip.txt to yaml")
>> those properties were demoted to optional and removed from the binding
>> example.
>> 
>> As for the compatibles:
>> - rockchip,px30-mipi-dsi      removed in this patch set
>> - rockchip,rk3128-mipi-dsi    never used
>> - rockchip,rk3288-mipi-dsi    added (invalid); later removed [1]
>> - rockchip,rk3399-mipi-dsi    removed in this patch set
>> - rockchip,rk3568-mipi-dsi    never used
>> - rockchip,rv1126-mipi-dsi    proposed (invalid); never accepted [2]
>> 
>> [1] 282e2e078ba5 ("ARM: dts: rockchip: Remove #address/#size-cells from rk3288 mipi_dsi")
>> [2] https://lore.kernel.org/all/20230731110012.2913742-12-jagan@edgeble.ai/
>> 
>> The #address-cells and #size-cells are useful (and required) in the
>> ports node and for panel(s), but those properties are declared in their
>> schemas already. Now that there are no remaining users, remove these
>> properties from the Rockchip specific extensions of the Synopsys
>> DesignWare MIPI DSI host controller.
>
> The change is fine, but your reasoning is flawed. These properties are 
> used if you define DSI devices on the "DSI bus" where the address of the 
> child devices are the DSI virtual channel. Often though that's just 0 
> and not really used, so you don't need it. 

Thanks for the explanation :-)

> The change is fine because these properties are defined in 
> dsi-controller.yaml, so specifying them here is redundant.

Indeed. Will fix in the next version.

Cheers,
  Diederik

>> 
>> Signed-off-by: Diederik de Haas <didi.debian@...ow.org>
>> ---
>>  .../bindings/display/rockchip/rockchip,dw-mipi-dsi.yaml     | 6 ------
>>  1 file changed, 6 deletions(-)
>> 
>> diff --git a/Documentation/devicetree/bindings/display/rockchip/rockchip,dw-mipi-dsi.yaml b/Documentation/devicetree/bindings/display/rockchip/rockchip,dw-mipi-dsi.yaml
>> index ccd71c5324af..0881e82deb11 100644
>> --- a/Documentation/devicetree/bindings/display/rockchip/rockchip,dw-mipi-dsi.yaml
>> +++ b/Documentation/devicetree/bindings/display/rockchip/rockchip,dw-mipi-dsi.yaml
>> @@ -58,12 +58,6 @@ properties:
>>    power-domains:
>>      maxItems: 1
>>  
>> -  "#address-cells":
>> -    const: 1
>> -
>> -  "#size-cells":
>> -    const: 0
>> -
>>  required:
>>    - compatible
>>    - clocks
>> -- 
>> 2.50.0
>> 


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