Re: [PATCH v3 1/2] arm64: dts: qcom: monaco: add lt8713sx bridge with displayport

[Vishnu Saini]

On Fri, Mar 13, 2026 at 07:01:57PM +0200, Dmitry Baryshkov wrote:
> On Fri, Mar 13, 2026 at 02:53:06PM +0530, Vishnu Saini wrote:
> > On Mon, Mar 09, 2026 at 09:19:45PM +0200, Dmitry Baryshkov wrote:
> > > On Mon, Mar 09, 2026 at 02:38:41PM +0530, Vishnu Saini wrote:
> > > > On Sun, Feb 22, 2026 at 09:16:54PM +0200, Dmitry Baryshkov wrote:
> > > > > On Sun, Feb 22, 2026 at 04:56:45AM +0530, Vishnu Saini wrote:
> > > > > > On Sun, Dec 28, 2025 at 05:49:30PM +0200, Dmitry Baryshkov wrote:
> > > > > > > On Sun, Dec 28, 2025 at 07:10:38PM +0530, Vishnu Saini wrote:
> > > > > > > > Monaco-evk has LT8713sx which act as DP to 3 DP output
> > > > > > > > converter. Edp PHY from monaco soc is connected to lt8713sx
> > > > > > > > as input and output of lt8713sx is connected to 3 mini DP ports.
> > > > > > > > 
> > > > > > > > Two ports are available in mainboard and one port
> > > > > > > > is available on Mezz board.
> > > > > > > > 
> > > > > > > > lt8713sx is connected to soc over i2c0 and with reset gpio
> > > > > > > > connected to pin6 of ioexpander5.
> > > > > > > > 
> > > > > > > > Enable the edp nodes from monaco and enable lontium lt8713sx
> > > > > > > > bridge node.
> > > > > > > > 
> > > > > > > > Co-developed-by: Prahlad Valluru <vvalluru@xxxxxxxxxxxxxxxx>
> > > > > > > > Signed-off-by: Prahlad Valluru <vvalluru@xxxxxxxxxxxxxxxx>
> > > > > > > > Signed-off-by: Vishnu Saini <vishnu.saini@xxxxxxxxxxxxxxxx>
> > > > > > > > ---
> > > > > > > >  arch/arm64/boot/dts/qcom/monaco-evk.dts | 89 +++++++++++++++++++++++++++++++++
> > > > > > > >  arch/arm64/boot/dts/qcom/monaco.dtsi    |  6 +++
> > > > > > > >  2 files changed, 95 insertions(+)
> > > > > > > > 
> > > > > > > > +
> > > > > > > > +	status = "okay";
> > > > > > > > +};
> > > > > > > > +
> > > > > > > > +&mdss_dp0_out {
> > > > > > > > +	data-lanes = <0 1 2 3>;
> > > > > > > > +	link-frequencies = /bits/ 64 <1620000000 2700000000 5400000000 8100000000>;
> > > > > > > > +	remote-endpoint = <&lt8713sx_dp_in>;
> > > > > > > 
> > > > > > > Does the bridge use DP signalling or does it use USB-C signalling here?
> > > > > > > And even if it is DP signalling, it should be correctly described as
> > > > > > > it uses signals coming from the QMP PHY. See how it's done for laptops
> > > > > > > with DP-HDMI convertors.
> > > > > > Yes, the LT8713SX is using native DP signalling, not USB‑C DP Alt‑Mode.
> > > > > > The QMP DP PHY is already implicitly part of the mdss_dp0 pipeline,
> > > > > > similar to other Qualcomm platforms where external DP bridges are connected. Because of that, I intentionally modeled the connection as:
> > > > > > MDSS DP controller -> LT8713SX bridge
> > > > > > This keeps the DT consistent with existing Qualcomm DP bridge descriptions, where the PHY is not represented as a separate graph endpoint unless there is external lane muxing or alternative signalling paths.
> > > > > > If you feel strongly that the DT should explicitly model:
> > > > > > MDSS DP controller -> QMP DP PHY → LT8713SX bridge
> > > > > > I can update the graph accordingly. Otherwise, please let me know if documenting this more clearly in the binding or commit message would be sufficient.
> > > > > 
> > > > > Please check how (and why) other boards handle the similar usecase of
> > > > > DP-to-HDMI bridges. To put it short, in your DT there is no notion that
> > > > > it is a native DP rather than USB-C signalling.
> > > > 
> > > > Sorry i couldn't find any good reference for DP-HDMI bridges to check signaling. I checked these
> > > > DP-HDMI bridges PS175, PS176, PS186, PS195, PS196, RTD2171, RTD2142, TI DP159, VM5200 but none of them 
> > > > wire DT graph endpoints, Please let me know if there are any specific DP-HDMI bridge you are referring to.
> > > > 
> > > > I looked for other references where USB‑C signaling is used, in those case the datapath always involves a
> > > > USB‑C controller/Type‑C mux/switch explicitly represented in the DT.
> > > > For native DP signaling, the common pattern is that the DP controller output is wired directly to a
> > > > DP connector/bridge, without any UCB‑C components in the path.
> > > 
> > > Yes. Please see qcom/x1p42100-lenovo-thinkbook-16.dts for the example.
> > 
> > Thank you for the reference. In qcom/x1p42100-lenovo-thinkbook-16.dts
> > I reviewed the HPG for x1p42100 and monaco, x1p42100 is having DP0/DP1/DP2 as USB/DP QMP PHY and DP3 is DP/eDP Phy, so DT graph wiring is defined as below:
> > mdss_dp0_out -> usb_1_ss0_qmpphy_dp_in -> usb_1_ss0_qmpphy_out
> > mdss_dp1_out -> usb_1_ss1_qmpphy_dp_in -> usb_1_ss1_qmpphy_out
> > 
> > mdss_dp3_out -> edp_panel_in
> > 
> > In Monaco DP0 is a eDP/DP phy, hence DT graph wiring is defined as below:
> > mdss_dp0_out -> lt8713sx_dp_in
> > 
> > I think Native DP signalig in this patch is align with the reference DT and HPG, please let me know if you are expecting any changes in the current DT graph wiring to make this clear.
> 
> I see, I totally forgot that it doesn't use the QMP USB+DP PHY.
> 
> Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxxxxxxxx>

Thank you, dependent dt patch is merged now, i will submit a new series with these patches on top of the branch. 
> 
> -- 
> With best wishes
> Dmitry