Re: [PATCH 1/2] dt-bindings:bridge Add LT7911EXC binding

[Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>]

On Tue, Apr 21, 2026 at 09:33:34AM +0800, 杨孙运 wrote:
> Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com> 于2026年4月20日周一 11:12写道：
> >
> > ote, your message didn't reach dri-devel. Please check why. You might
> > need to switch to B4 Web relay submission, if there are any issues
> > with the SMTP on your side.
> >
> > On Mon, 20 Apr 2026 at 05:34, <syyang@lontium.com> wrote:
> > >
> > > From: Sunyun Yang <syyang@lontium.com>
> > >
> > > -binding for lt7911exc.
> >
> > Less is more, but here please settle for slightly more information
> > about the chip.
> >
> 
> It will be modified in the next version.
> 
> > >
> > > Signed-off-by: Sunyun Yang <syyang@lontium.com>
> > > ---
> > >  .../display/bridge/lontium,lt7911exc.yaml     | 91 +++++++++++++++++++
> > >  1 file changed, 91 insertions(+)
> > >  create mode 100644 Documentation/devicetree/bindings/display/bridge/lontium,lt7911exc.yaml
> > >
> > > diff --git a/Documentation/devicetree/bindings/display/bridge/lontium,lt7911exc.yaml b/Documentation/devicetree/bindings/display/bridge/lontium,lt7911exc.yaml
> > > new file mode 100644
> > > index 000000000000..54a73d41635a
> > > --- /dev/null
> > > +++ b/Documentation/devicetree/bindings/display/bridge/lontium,lt7911exc.yaml
> > > @@ -0,0 +1,91 @@
> > > +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
> > > +%YAML 1.2
> > > +---
> > > +$id: http://devicetree.org/schemas/display/bridge/lontium,lt7911exc.yaml#
> > > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > > +
> > > +title: Lontium LT7911EXC eDP to MIPI Bridge
> > > +
> > > +maintainers:
> > > +  - Sunyun Yang <syyang@lontium.com>
> > > +
> > > +properties:
> > > +  compatible:
> > > +    enum:
> > > +      - lontium,lt7911exc
> > > +
> > > +  reg:
> > > +    maxItems: 1
> > > +
> > > +  reset-gpios:
> > > +    maxItems: 1
> > > +    description: GPIO connected to RST_ pin.
> > > +
> > > +  vdd-supply:
> > > +    description: Regulator for 1.2V MIPI phy power.
> > > +
> > > +  vcc-supply:
> > > +    description: Regulator for 3.3V IO power.
> > > +
> > > +  ports:
> > > +    $ref: /schemas/graph.yaml#/properties/ports
> > > +
> > > +    properties:
> > > +      port@0:
> > > +        $ref: /schemas/graph.yaml#/properties/port
> > > +        description: Video port for mipi dsi output.
> >
> > MIPI, DSI
> >
> It will be use MIPI DSI,  in the next version.
> 
> > > +
> > > +      port@1:
> > > +        $ref: /schemas/graph.yaml#/properties/port
> > > +        description: Video port for eDP input.
> > > +
> > > +    required:
> > > +      - port@0
> > > +      - port@1
> > > +
> > > +required:
> > > +  - compatible
> > > +  - reg
> > > +  - reset-gpios
> > > +  - vdd-supply
> > > +  - vcc-supply
> > > +  - ports
> > > +
> > > +additionalProperties: false
> > > +
> > > +examples:
> > > +  - |
> > > +    #include <dt-bindings/gpio/gpio.h>
> > > +    i2c {
> > > +        #address-cells = <1>;
> > > +        #size-cells = <0>;
> > > +
> > > +        mipi-bridge@41 {
> > > +            compatible = "lontium,lt7911exc";
> > > +            reg = <0x41>;
> > > +            reset-gpios = <&gpy8 8 GPIO_ACTIVE_HIGH>;
> >
> > Reset pins are usually active low.
> >
> if reset pins use active low, lt7911exc_reset function needs to be modified to:
> static void lt7911exc_reset(struct lt7911exc *lt7911exc)
> {
>     gpiod_set_value_cansleep(lt7911exc->reset_gpio, 0);
>     msleep(20);
> 
>     gpiod_set_value_cansleep(lt7911exc->reset_gpio, 1);
>     msleep(20);
> 
>     gpiod_set_value_cansleep(lt7911exc->reset_gpio, 0);
>     msleep(400);
> 
>     dev_dbg(lt7911exc->dev, "lt7911exc reset");
> }
> 
> I think the two are essentially the same. Please confirm whether I
> need to make the change?

If the GPIO is active-low in the hardware, it should be declared so in
DT.

> 
> > > +            vdd-supply = <&lt7911exc_1v2>;
> > > +            vcc-supply = <&lt7911exc_3v3>;
> > > +
> > > +            ports {
> > > +                #address-cells = <1>;
> > > +                #size-cells = <0>;
> > > +
> > > +                port@0 {
> > > +                    reg = <0>;
> > > +
> > > +                    bridge_out: endpoint {
> > > +                        remote-endpoint = <&panel_in>;
> > > +                    };
> > > +                };
> > > +
> > > +                port@1 {
> > > +                    reg = <1>;
> > > +
> > > +                    bridge_in: endpoint {
> > > +                        remote-endpoint = <&edp_out>;
> > > +                    };
> > > +                };
> > > +            };
> > > +        };
> > > +    };
> >
> > --
> > With best wishes
> > Dmitry

-- 
With best wishes
Dmitry