Re: [PATCH] arm64: dts: qcom: sm8550-qrd: add display and panel

[Krzysztof Kozlowski]

On 16/05/2023 17:26, Konrad Dybcio wrote:
>>>> +&mdss_mdp {
>>>> +	status = "okay";
>>>> +};
>>> This should also be enabled by default, MDSS is useless when MDP is
>>> disabled.
>>
>> But don't we want to disable both when display is not used (not connected)?
> The MDSS bus device only has a 0x1000 slice of the 0x90000-long "full MDSS",
> the rest is probed with MDP/DPU. It also calls of_something_populate that
> make DSI, DSIPHY and DP/HDMI probe. But all of them ultimately need a graph
> handle to MDP.
> 
> If we have a display (of any kind), MDP has to be enabled (or the display
> engine will not have a way to be programmed).
> 
> If we don't, enabling MDSS makes no sense as all of the hardware will be
> shut down right after probing.
> 
> So I'd say either both or none.

Yes, so the current state - both disabled - is matching it.

Best regards,
Krzysztof