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

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Message-ID: <cysgc3zxp7qx3gwrqmr6ntvmeyw7sodxjs2a5sil6qw3wk6oav@il6wvs234j5g>
Date: Tue, 4 Mar 2025 02:06:25 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Abhinav Kumar <quic_abhinavk@...cinc.com>
Cc: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>, 
	Rob Clark <robdclark@...il.com>, Sean Paul <sean@...rly.run>, 
	Marijn Suijten <marijn.suijten@...ainline.org>, David Airlie <airlied@...il.com>, 
	Simona Vetter <simona@...ll.ch>, Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, 
	Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, 
	Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, 
	Conor Dooley <conor+dt@...nel.org>, Krishna Manikandan <quic_mkrishn@...cinc.com>, 
	Jonathan Marek <jonathan@...ek.ca>, Kuogee Hsieh <quic_khsieh@...cinc.com>, 
	Neil Armstrong <neil.armstrong@...aro.org>, linux-arm-msm@...r.kernel.org, dri-devel@...ts.freedesktop.org, 
	freedreno@...ts.freedesktop.org, devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Srini Kandagatla <srinivas.kandagatla@...aro.org>
Subject: Re: [PATCH v2 05/16] dt-bindings: display/msm: dp-controller: Add
 SM8750

On Mon, Mar 03, 2025 at 01:23:11PM -0800, Abhinav Kumar wrote:
> 
> 
> On 2/24/2025 7:14 PM, Dmitry Baryshkov wrote:
> > On Mon, 24 Feb 2025 at 20:59, Abhinav Kumar <quic_abhinavk@...cinc.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.

Ack, thanks.

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>


-- 
With best wishes
Dmitry