Re: [PATCH v2 05/16] dt-bindings: display/msm: dp-controller: Add SM8750

[Abhinav Kumar <quic_abhinavk@quicinc.com>]

On 2/24/2025 7:14 PM, Dmitry Baryshkov wrote:
> On Mon, 24 Feb 2025 at 20:59, Abhinav Kumar <quic_abhinavk@quicinc.com> wrote:
>>
>>
>>
>> On 2/19/2025 9:08 AM, Dmitry Baryshkov wrote:
>>> On Wed, Feb 19, 2025 at 06:02:20PM +0100, Krzysztof Kozlowski wrote:
>>>> On 17/02/2025 19:58, Dmitry Baryshkov wrote:
>>>>> On Mon, Feb 17, 2025 at 05:41:26PM +0100, Krzysztof Kozlowski wrote:
>>>>>> Add DisplayPort controller for Qualcomm SM8750 SoC which so far looks
>>>>>> fully compatible with earlier SM8650 variant.
>>>>>
>>>>> As that became a question for QCS8300, does SM8750 also support exactly
>>>>> two MST streams?
>>>>
>>>> v1.5 of DP (starting from SA8775p , then SM8650 and SM8750) support 4x
>>>> MST for DPTX0 and 2x MST for DPTX1.
>>>>
>>>> The DP in SM8650 and SM8750 are identical, according to datasheet (v1.5.1).
>>>
>>> Hmm. This also means that QCS8300 is compatible with SM8650. I'll let
>>> Abhinav comment here.
>>>
>>
>> DP version by itself is not a good measure of whether the controller can
>> support 4 streams or not.
>>
>> Firstly, sm8650/sm8750 do not have a DPTX1 so we are only discussing
>> about DP TX0.
>>
>> Coming to the QCS8300 Vs sm8650/sm8750, even though the DP controller
>> version is the same, there is no HW support for more than 2 streams on
>> sm8650/sm8750 because there are no INTF blocks to drive 4 streams.
>>
>> On sm8650/sm8750, only INTF_0 and INTF_3 can be used for DP. Hence 2
>> streams.
>>
>> Whereas on Monaco, we have INTF_0, INTF_3, INTF_6 and INTF_7 capable of
> 
> No idea what Monaco is, most likely it is some platform. Please use
> SoC names in public.
> 

Monaco is indeed QCS8300. I usually do use SoC names, in this instance 
just intuitively ended up using the internal one as I use it often.

>> driving DP. Hence 4 streams.
>>
>> Let me know if there are more questions.
> 
> How many stream clocks are present on those platforms? I'm asking
> because there is a small, but not non-existing difference between 'DPs
> are not completely compatible / the same' and 'DPs are fully
> compatible but different DPU blocks impose different restrictions on
> the number of MST streams'.
> 

I have confirmed this internally. sm8650/sm8750 have only 2 stream 
clocks and not 4.