Other Parts Discussed in Thread: SN65DSI84
Dear Expert
Problem description:
The test showed that the sn65dsi83 of imx8 occasionally showed a black or white screen when turned on, and the data line from LVDS to LCD showed no signal. In addition, the E5 register of sn65dsi83 I2C often showed 0x81, and sometimes other errors occurred. However, by setting sn65dsi83 to test mode through the i2c instruction, the data line had a signal.
Could you please ask the FAE from the original manufacturer of the sn65dsi83 chip to help identify the cause and provide a solution.
1) Test the MIPI terminal waveform for output when the screen is black or white
2) The waveform of LVDS under normal conditions is as follows, but the waveform shown in the figure below does not appear when abnormal .
The sn65dsi83 i2c data read during normal and abnormal times is:
i2cdump -f -y 1 0x2d
No size specified (using byte-data access)
0 1 2 3 4 5 6 7 8 9 a b c d e f
00: 35 38 49 53 44 20 20 20 01 00 85 10 00 01 00 00
10: 26 00 27 00 00 00 00 00 1c 00 03 00 00 00 00 00
20: 00 04 00 00 00 03 00 00 21 00 00 00 02 00 00 00
30: 02 00 00 00 a0 00 13 00 a0 00 13 00 00 00 00 00
40: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
50: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
60: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
70: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
90: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
e0: 00 00 00 00 00 80 00 00 00 00 00 00 00 00 00 00
f0: 00 00 00 00 40 00 00 80 00 00 00 00 00 00 00 00
The software+hardware environment is:
1) CPU: IMX8MM MIPI to LVDS chip: sn65dsi83 screen LCD: G121XCE_ L01
2) Kernel: linux5.4.70
3) The kernel device tree is configured as:
&i2c2 {
clock-frequency = <400000>;
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_i2c2>;
status = "okay";
dsi_lvds_bridge: sn65dsi84@2d {
compatible = "ti,sn65dsi83";
reg = <0x2d>;
ti,dsi-lanes = <4>;
ti,lvds-format = <0>;
ti,lvds-bpp = <24>;
ti,width-mm = <210>;
ti,height-mm = <157>;
pinctrl-names = "default";
pinctrl-0 = <&lvds_en>;
enable-gpios = <&gpio3 14 GPIO_ACTIVE_HIGH>;
status = "okay";
display-timings {
native-mode = <&timing0>;
timing0: 1024x768_60Hz {
clock-frequency = <66000000>;
hactive = <1024>;
vactive = <768>;
hback-porch = <160>;
hfront-porch = <160>;
hsync-len = <2>;
vback-porch = <19>;
vfront-porch = <19>;
vsync-len = <2>;
hsync-active = <1>;
vsync-active = <1>;
de-active = <1>;
pixelclk-active = <0>;
};
};
port {
lvds_from_dsi: endpoint {
remote-endpoint = <&dsi_to_lvds>;
};
};
};
};
Below is sch:
