Re: [PATCH v3 1/6] dt-bindings: display: panel: Add Novatek NT35532 LCD DSI

[cristian_ci]

On Saturday, March 21st, 2026 at 17:46, Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxxxxxxxx> wrote:

> On Sat, Mar 21, 2026 at 05:23:20PM +0100, Cristian Cozzolino via B4 Relay wrote:
> > From: Cristian Cozzolino <cristian_ci@xxxxxxxxxxxxxx>
> >
> > Document Novatek NT35532-based DSI display panel.
> >
> > Signed-off-by: Cristian Cozzolino <cristian_ci@xxxxxxxxxxxxxx>
> > ---
> >  .../bindings/display/panel/novatek,nt35532.yaml    | 77 ++++++++++++++++++++++
> >  MAINTAINERS                                        |  5 ++
> >  2 files changed, 82 insertions(+)
> 
> > +allOf:
> > +  - $ref: panel-common.yaml#
> > +
> > +properties:
> > +  compatible:
> > +    const: novatek,nt35532
> 
> This is not enough to identify the panel. This name identifies the
> controller inside the panel, however the exact settings (and the
> behaviour) would depend on the exact TFT "glass" used with this
> controller. Downstream usually doesn't care that much and frequently
> just uses the controller name or the the controller with some kind of
> "description" like ("wqhd-dsc-cmd").

Ok but I just don't understand the following: I'd like to know (also 
considering that I find it difficult to find someone, outside of this 
ML, available to discuss this stuff, specifically) exactly why the 
current bindings are not enough.
I mean: looking at schematics and datasheets of other similar devices 
and based on observations about my device, I believe the generic bindings 
approach for nt35532 works quite well for panels.
Novatek made the IC first and then whoever buys it can be a display 
vendor. If we talk about downstream, differences between panels are described 
there (i.e. my panel makes use of four supplies, while other ones could use 
a different configuration).

> What does it mean for the upstream:
> - Try identifying the actual panel used for the phones. Sometimes
>   googling for spare or replacement parts would reveal such a name.
>   Sometimes it can be seen as a marking on the cable or on the backside
>   of the panel (again, googling).

It seems that 'google' approach fails, in my case :( (I only know that 
the vendor assigned Smartron the work to design the HW - but SW too - 
of the device. Nevertheless, Smartron is neither OEM nor ODM, so the 
company was relying, at the time, on a series of chinese manufacturers to provide 
parts required for this device, including panel suppliers: in general, 
the list of panel suppliers for Smartron includes BOE, Tianma and other known 
companies. So, this panel may be any of those, paired with NT35532, and work 
anyway). Unfortunately, even if marking on the cable is known, that doesn't 
identify the panel but the cable itself (which is available on the market, 
though), instead, in this case.

> - If not found, come up with some artificial identifier that would
>   identify the controller+glass combo (e.g. "tianma,fhd-video" or
>   "lenovo,j606f-boe-nt36523w" (where lenovo,j6006f is a device name and
>   boe is a "supplier").

Assuming that resources available which I've as source of information 
for this panel are limited (the ones also described in v1's review thread), 
my vendor devicetree describes the panel in  'qcom,mdss_dsi_nt35532_1080p_cs_video' 
node and makes use of:

qcom,mdss-dsi-panel-name = "nt35532 1080p cs video mode dsi panel";

property. Until now, close-to-mainline devicetree I was using the following 
compatible for the panel:

compatible = "flipkart,rimob-nt35532-cs";

and I'm not sure about the exact meaning of 'cs' suffix. I cannot state 'CS' 
as panel supplier and use that upstream without proof/evidence. What do 
you suggest, in this regard?


Cristian
 
> - Either use both strings for compat property:
>   compatible = "tianma,fhd-video", "novatek,nt36672a"
>   or just the first one.
> 
> > +
> > +  reg:
> > +    maxItems: 1
> > +
> > +  backlight: true
> > +  reset-gpios: true
> > +
> > +  avdd-supply:
> > +    description: positive boost supply regulator
> > +
> > +  avee-supply:
> > +    description: negative boost supply regulator
> > +
> > +  vci-supply:
> > +    description: regulator that supplies the analog voltage
> > +
> > +  vddam-supply:
> > +    description: power supply for MIPI interface
> > +
> > +  vddi-supply:
> > +    description: regulator that supplies the I/O voltage
> > +
> > +  port: true
> > +
> > +required:
> > +  - compatible
> > +  - reg
> > +  - reset-gpios
> > +  - vddi-supply
> > +  - port
> > +
> > +additionalProperties: false
> > +
> > +examples:
> > +  - |
> > +    #include <dt-bindings/gpio/gpio.h>
> > +
> > +    dsi {
> > +        #address-cells = <1>;
> > +        #size-cells = <0>;
> > +
> > +        panel@0 {
> > +            compatible = "novatek,nt35532";
> > +            reg = <0>;
> > +
> > +            backlight = <&pmi8950_wled>;
> > +            reset-gpios = <&tlmm 61 GPIO_ACTIVE_LOW>;
> > +            avdd-supply = <&lab>;
> > +            avee-supply = <&ibb>;
> > +            vci-supply = <&pm8953_l17>;
> > +            vddi-supply = <&pm8953_l6>;
> > +
> > +            port {
> > +                panel_in: endpoint {
> > +                    remote-endpoint = <&dsi0_out>;
> > +                };
> > +            };
> > +        };
> > +    };
> > +...
> > diff --git a/MAINTAINERS b/MAINTAINERS
> > index a626dee5c106..8ed2866bbd6e 100644
> > --- a/MAINTAINERS
> > +++ b/MAINTAINERS
> > @@ -8171,6 +8171,11 @@ T:	git https://gitlab.freedesktop.org/drm/misc/kernel.git
> >  F:	Documentation/devicetree/bindings/display/panel/novatek,nt35510.yaml
> >  F:	drivers/gpu/drm/panel/panel-novatek-nt35510.c
> >
> > +DRM DRIVER FOR NOVATEK NT35532 PANELS
> > +M:	Cristian Cozzolino <cristian_ci@xxxxxxxxxxxxxx>
> > +S:	Maintained
> > +F:	Documentation/devicetree/bindings/display/panel/novatek,nt35532.yaml
> > +
> >  DRM DRIVER FOR NOVATEK NT35560 PANELS
> >  M:	Linus Walleij <linusw@xxxxxxxxxx>
> >  S:	Maintained
> >
> > --
> > 2.53.0
> >
> >
> 
> --
> With best wishes
> Dmitry
>