linux-kernel - Re: [PATCH v2] dt-bindings: display: ti,am65x-dss: Fix AM62L DSS reg and clock constraints

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Message-ID: <4b554339-95e1-4980-8899-57ba637ba80c@ti.com>
Date: Fri, 6 Feb 2026 19:48:59 +0530
From: Swamil Jain <s-jain1@...com>
To: Krzysztof Kozlowski <krzk@...nel.org>
CC: <jyri.sarha@....fi>, <tomi.valkeinen@...asonboard.com>,
	<maarten.lankhorst@...ux.intel.com>, <mripard@...nel.org>,
	<tzimmermann@...e.de>, <airlied@...il.com>, <simona@...ll.ch>,
	<robh@...nel.org>, <krzk+dt@...nel.org>, <conor+dt@...nel.org>,
	<devarsht@...com>, <dri-devel@...ts.freedesktop.org>,
	<devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<praneeth@...com>, <vigneshr@...com>
Subject: Re: [PATCH v2] dt-bindings: display: ti,am65x-dss: Fix AM62L DSS reg
 and clock constraints

Hi Krzysztof,

On 2/5/26 18:55, Krzysztof Kozlowski wrote:
> On Thu, Jan 29, 2026 at 08:36:01PM +0530, Swamil Jain wrote:
>> The AM62L DSS [1] support incorrectly used the same register and
>> clock constraints as AM65x, but AM62L has a single video port.
>>
>> Fix this by adding conditional constraints that properly define the
>> register regions and clocks for AM62L DSS (single video port) versus
>> other AM65x variants (dual video port).
>>
>> [1]: Section 12.7 (Display Subsystem and Peripherals)
>> Link : https://www.ti.com/lit/pdf/sprujb4
>>
>> Fixes: cb8d4323302c ("dt-bindings: display: ti,am65x-dss: Add support for AM62L DSS")
>> Cc: stable@...r.kernel.org
>>
> 
> There are never blank lines between tags.
> 

Sorry, will fix this.

>> Signed-off-by: Swamil Jain <s-jain1@...com>
>> ---
>> Changelog:
>> v1->v2:
>> - Remove oneOf from top level constraints, it makes bindings redundant
>> - Remove minItems from top level constraints
>> - "dma-coherent" property shouldn't be changed in v1 itself
>> - Add description for reg-names, clock and clock-names
>> - Add constraints specific to AM62L and for other SoCs within allOf
>>    check
>>
>> Link to v1:
>> https://lore.kernel.org/all/20251224133150.2266524-1-s-jain1@ti.com/
>> ---
>>   .../bindings/display/ti/ti,am65x-dss.yaml     | 93 +++++++++++++------
>>   1 file changed, 67 insertions(+), 26 deletions(-)
>>
>> diff --git a/Documentation/devicetree/bindings/display/ti/ti,am65x-dss.yaml b/Documentation/devicetree/bindings/display/ti/ti,am65x-dss.yaml
>> index 38fcee91211e..dbc9d754cf9e 100644
>> --- a/Documentation/devicetree/bindings/display/ti/ti,am65x-dss.yaml
>> +++ b/Documentation/devicetree/bindings/display/ti/ti,am65x-dss.yaml
>> @@ -36,38 +36,18 @@ properties:
>>     reg:
>>       description:
>>         Addresses to each DSS memory region described in the SoC's TRM.
>> -    items:
>> -      - description: common DSS register area
>> -      - description: VIDL1 light video plane
>> -      - description: VID video plane
>> -      - description: OVR1 overlay manager for vp1
>> -      - description: OVR2 overlay manager for vp2
>> -      - description: VP1 video port 1
>> -      - description: VP2 video port 2
>> -      - description: common1 DSS register area
> 
> No, I do not understand this change. We spoke so many times, documented
> it, wrotre on presentation slides: broadest constraints are always
> defined in top level. TI received this feedback more than once.
> 

There is no superset constraints since am62l register sequence (common, 
vidl1, ovr1, vp1, common1) is different than non-am62l SoCs (common, 
vidl1, vid, ...-> here it is different), so thought to adopt this 
approach where there is if-else block for each SoC and ran this through 
dt-bindings check as well, looking at the replies maybe I misunderstood 
what the suggestion was, reading the reply as I understand below is the 
suggestion:

```
reg:
     description:
       Addresses to each DSS memory region described in the SoC's TRM.
     oneOf:
       - items:
           - description: common DSS register area
           - description: VIDL1 light video plane
           - description: VID video plane
           - description: OVR1 overlay manager for vp1
           - description: OVR2 overlay manager for vp2
           - description: VP1 video port 1
           - description: VP2 video port 2
           - description: common1 DSS register area
       - items:
           - description: common DSS register area
           - description: VIDL1 light video plane
           - description: OVR1 overlay manager for vp1
           - description: VP1 video port 1
           - description: common1 DSS register area

.....(Similarly for reg-names, clocks, clock-names,...)

allOf:
   - if:
       properties:
         compatible:
           contains:
             const: ti,am62l-dss
     then:
       properties:
         clock-names:
           maxItems: 2
         clocks:
           maxItems: 2
         reg:
           maxItems: 5
     else:
       properties:
         clock-names:
           minItems: 3
         clocks:
           minItems: 3
         reg:
           minItems: 8

```

Could you please confirm on this?

Regards,
Swamil.


> Sorry guys, but you are not individual contributors which do it in spare
> time. Why the same feedback - already documented - has to be repeated?
> 
> Best regards,
> Krzysztof
> 
>