Re: [PATCH 1/3] arm64: dts: qcom: lemans-evk: Add LVDS display overlay

[Vishnu Saini]

On Wed, Jul 22, 2026 at 04:44:14PM +0300, Dmitry Baryshkov wrote:
> On Sun, Jul 19, 2026 at 11:35:06PM +0530, Vishnu Saini wrote:
> > The Lemans EVK IFP mezzanine supports LVDS display output using the
> > Lontium LT9211C DSI-to-LVDS bridge. The bridge is connected to the
> > DSI0 output and drives a dual-channel 1920x1080 LVDS panel in
> > VESA-24 mapping.
> > 
> > Add a DTBO overlay, lemans-evk-lvds-boe,dv215fhm-r01.dtso, that wires
> > up the LT9211C bridge on I2C1 (address 0x2d) with reset on GPIO37,
> > a panel-lvds node describing the 476x268mm 1080p panel timing, and
> > an LCD display bias regulator supplied through the GPIO expander.
> > DSI power is provided by vreg_s4a.
> > 
> > The overlay is built as a composite DTB combining the base
> > lemans-evk.dtb, the IFP mezzanine overlay, and this LVDS overlay.
> > 
> > Signed-off-by: Vishnu Saini <vishnu.saini@xxxxxxxxxxxxxxxx>
> > ---
> >  arch/arm64/boot/dts/qcom/Makefile                  |   4 +
> >  .../dts/qcom/lemans-evk-lvds-boe,dv215fhm-r01.dtso | 127 +++++++++++++++++++++
> >  2 files changed, 131 insertions(+)
> > 
> > +	model = "Qualcomm Technologies, Inc. Lemans-evk Mezzanine Lvds";
> 
> EVK, LVDS.
Will correct this in next revision. 
> > +
> > +	panel_lvds: panel-lvds {
> > +		compatible = "boe,dv215fhm-r01", "panel-lvds";
> 
> Thinking about it, does your panel have EDID? Is it readable from the
> device via the I2C bus?

The panel doesn't have edid and not connected with I2C bus. 
> My major concern is that if the user changes the LVDS panel, they'd need
> a new DTBO.
> 
> Would it make sense to implement EDID-based handling (like it's done in
> panel-edp)?
Your concern is valid, edid read will not work for this panel.

> > +		data-mapping = "vesa-24";
> > +		width-mm = <476>;
> > +		height-mm = <268>;
> > +		power-supply = <&lcd_disp_bias>;
> > +		status = "okay";
> > +
> > +		panel-timing {
> > +			clock-frequency = <148500000>;
> > +			hactive = <1920>;
> > +			vactive = <1080>;
> > +			hfront-porch = <88>;
> > +			hback-porch = <148>;
> > +			hsync-len = <44>;
> > +			vfront-porch = <4>;
> > +			vback-porch = <36>;
> > +			vsync-len = <5>;
> > +			de-active = <1>;
> > +		};
> 
> [..]
> 
> > +
> > +&i2c1 {
> > +	#address-cells = <1>;
> > +	#size-cells = <0>;
> > +	pinctrl-names = "default";
> > +	pinctrl-0 = <&qup_i2c1_default>;
> > +	status = "okay";
> 
> Empty lines before the status property (here and later).
will correct this in next revision 
> > +
> 
> -- 
> With best wishes
> Dmitry