Re: [PATCH v4 3/4] arm64: dts: qcom: shikra-cqm-evk: Enable display and add ili7807s panel

[Dmitry Baryshkov]

On Wed, Sep 23, 2026 at 04:16:21PM +0530, Arpit Saini wrote:
> Hi Dmitry,
> 
> On 9/22/2026 9:33 PM, Dmitry Baryshkov wrote:
> > On Wed, Sep 16, 2026 at 02:41:20PM +0530, Nabige Aala wrote:
> >> From: Arpit Saini <arpit.saini@xxxxxxxxxxxxxxxx>
> >>
> >> Enable the Shikra MDSS display subsystem on the Qualcomm
> >> Shikra CQM EVK board and add the DLC0697 MIPI DSI display
> >> panel node. Pin pm4125_l5 to 1.232V with regulator-allow-set-load
> >> for DSI PHY PLL stability.
> >>
> >> Signed-off-by: Arpit Saini <arpit.saini@xxxxxxxxxxxxxxxx>
> >> Signed-off-by: Nabige Aala <nabige.aala@xxxxxxxxxxxxxxxx>
> >> ---
> >>  arch/arm64/boot/dts/qcom/shikra-cqm-evk.dts | 118 ++++++++++++++++++++++++++++
> >>  1 file changed, 118 insertions(+)
> >>
> >> +
> >> +&mdss_dsi0 {
> >> +	vdda-supply = <&pm4125_l5>;
> >> +
> >> +	status = "okay";
> >> +
> >> +	panel@0 {
> >> +		compatible = "dlc,dlc0697", "ilitek,ili7807s";
> >> +		reg = <0>;
> >> +
> >> +		reset-gpios = <&tlmm 3 GPIO_ACTIVE_LOW>;
> >> +
> >> +		vddi-supply = <&pm4125_l15>;
> >> +		avdd-supply = <&vreg_disp_p>;
> >> +		avee-supply = <&vreg_disp_n>;
> >> +
> >> +		pinctrl-0 = <&panel_rst_n &panel_te_pin &panel_bl_en>;
> > 
> > As far as I remember, your panel_bl_en enables an external regulator.
> > Why is it not described in this way?
> > 
> 
> panel_bl_en is a Qcom's daughter card specific platform signal , it does not feed into the panel.
> 
> It is a board-level GPIO on the CQM EVK daughter card used purely for
> platform power sequencing.
> 
> Adding panel_bl_en as an external regulator would be misleading and incorrect from a hardware perspective,
> as it is not directly going into the panel.

Well... Aren't VREG_WLED and WLED_SIN1 / SIN2 directly going to the
panel?

> 
> for the CQM EVK, the backlight is MIPI DCS driven and panel_bl_en is a
> platform-specific sequencing pin, making pinctrl states the
> appropriate binding here.
> 
> Could you please take a look at earlier discussion we had and let us know your thoughts ?
> 
> https://lore.kernel.org/all/29ca6303-4368-4aeb-b82f-039aa252780a@xxxxxxxxxxxxxxxx/

Exactly. The diagram there shows that GPIO 91 (panel_bl_en) is an enable
signal for the WLED regulator, whose output is then fed to the panel.

-- 
With best wishes
Dmitry