IMX8MM: Display output is not proper on panel

[Raghavendra]

Hi Team,

We are working on IMX8MM custom board 10.1 inch LVDS display bring-up connected through SN65DSI83 bridge (IMX8MM ==> MIPI-DSI ==> LVDS bridge ==> Panel).

there is no proper display output on panel. not able to see the images/activities clearly.

The parameters of display are as below.

Below are the dtsi changes made in the source code.

&i2c2 {
        clock-frequency = <400000>;
        pinctrl-names = "default";
        pinctrl-0 = <&pinctrl_i2c2>;
        status = "okay";

        lvds_bridge: sn65dsi83@2c {
                compatible = "ti,sn65dsi83";
                reg = <0x2c>;
                ti,dsi-lanes = <4>;
                ti,lvds-format = <2>;
                ti,lvds-bpp = <24>;
                ti,lvds-channels = <1>;
                ti,width-mm = <260>;
                ti,height-mm = <183>;
                enable-gpios = <&gpio2 9  GPIO_ACTIVE_HIGH>;
                interrupt-parent = <&gpio2>;
                interrupts = <8 IRQ_TYPE_LEVEL_HIGH>;
                pinctrl-names = "default";
                pinctrl-0 = <&pinctrl_dsi_lvds_bridge>;
                status = "okay";

                display-timings {
                        lvds {
                                clock-frequency = <72400000>;
                                hactive = <1280>;
                                vactive = <800>;
                                hback-porch = <88>;
                                hfront-porch = <72>;
                               vback-porch = <23>;
                                vfront-porch = <15>;
                                hsync-len = <80>;
                                vsync-len = <10>;
                        };
                };

                port {
                        sn65dsi83_in: endpoint {
                                remote-endpoint = <&dsim_to_sn65dsi8>;
                        };
                };
        };

Image displayed on panel:

Expected images to be displayed:

Could you please help us to review the changes.

Thanks,

Raghavendra

[Raghavendra]

Hi,

yes, now image displayed on panel is stable after fine tuning all parameters.

tested long runs at this stage.

In your case, try changing LVDS clock and observe if any change in flicker and continue to tune all blanking parameters. 

Thanks,

Raghavendra

[leandroschmitz]

Hi Raghavendra,

can you share the parameter values that work for you?

I've test a lot of combination following some rules to calculate Pixel Clock, and until now I do not have a good image in my screen.

Thanks

Leandro

[leandroschmitz]

I think  hsync-len should be between 1 and 40.

I've a similar LCD Panel, I try a lot of diferentes parameters but the image does not stabilize.

Let me know if you get um stable image successful in that.