Re: [PATCH v3 04/15] dt-bindings: display: ti,am65x-dss: Add ti,dpi-io-ctrl

[Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>]

Hi,

On 30/05/2026 11:58, Krzysztof Kozlowski wrote:
> On Fri, May 29, 2026 at 11:45:34AM +0300, Tomi Valkeinen wrote:
>> The DPI output pipeline in K3 SoCs contains the display subsystem (DSS)
>> which produces the in-SoC parallel video signal, and a DPI block which
>> adjusts the signal to the external MIPI DPI output.
>>
>> The DSS IP has registers to configure whether the data and sync signals
>> are driven on rising or falling clock edge, and on some SoCs these are
>> automatically conveyed to the DPI block which needs that configuration
>> to properly output the MIPI DPI signal.
>>
>> However, on some SoCs the DPI block configuration has to be done
>> manually, using an extra register outside the DSS, DPI0_CLK_CTRL in
>> MAIN_CTRL_MMR_CFG0 block, which controls the DPI block's behavior.
> 
> Why don't you constrain this properyy per SoC in such case? Why is it
> applicable to each SoC, even though you said it is done via DSS IP
> registers?

Good point. I'll restrict per SoC.

>> Currently the DPI0_CLK_CTRL is never written, so it's always 0, meaning
>> the data and sync are always driven on a rising clock edge regardless of
>> the DSS configuration.
>>
>> Add 'ti,dpi-io-ctrl' property, which contains phandle to the
>> MAIN_CTRL_MMR_CFG0 block and the offset to the DPI0_CLK_CTRL register,
>> so that the DSS driver can configure the data and sync signals
>> correctly.
>>
>> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
>> ---
>>   .../devicetree/bindings/display/ti/ti,am65x-dss.yaml          | 11 +++++++++++
>>   1 file changed, 11 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/display/ti/ti,am65x-dss.yaml b/Documentation/devicetree/bindings/display/ti/ti,am65x-dss.yaml
>> index 588d72d4ec0d..902ae2122d86 100644
>> --- a/Documentation/devicetree/bindings/display/ti/ti,am65x-dss.yaml
>> +++ b/Documentation/devicetree/bindings/display/ti/ti,am65x-dss.yaml
>> @@ -113,6 +113,17 @@ properties:
>>         and OLDI_CLK_IO_CTRL registers. This property is needed for OLDI
>>         interface to work.
>>   
>> +  ti,dpi-io-ctrl:
>> +    $ref: /schemas/types.yaml#/definitions/phandle-array
>> +    description:
>> +      phandle to a syscon device node containing the DPI0_CLK_CTRL register,
>> +      with the offset to DPI0_CLK_CTRL as an argument.
>> +    maxItems: 1
> 
> Drop
> 
>> +    items:
>> +      items:
> 
> missing '-'. See other examples of phandle-array, for example one of
> the first search results: qcom,ssc-block-bus.yaml
Thanks, I'll use that form.

  Tomi