Hello,
we have an Apalis V1.1B imx8 module mounted on a custom board and we have some problems with the DDC bus in HDMI. The HDMI works fine (the display works) but it gives the following error:
[drm:cdns_hdmi_connector_get_modes] ERROR Invalid edid
The dts that we are using is based on the ixora V1.2 dts and we have added the following to enable the DDC I2C bus:
pinctrl_lpi2c0: lpi2c0grp {
fsl,pins = <
/*
IMX8QM_HDMI_TX0_TS_SCL_DMA_I2C0_SCL 0x04000022
IMX8QM_HDMI_TX0_TS_SDA_DMA_I2C0_SDA 0x04000022
*/
IMX8QM_HDMI_TX0_TS_SCL_HDMI_TX0_I2C0_SCL 0xc600004c
IMX8QM_HDMI_TX0_TS_SDA_HDMI_TX0_I2C0_SDA 0xc600004c
>;
};
/* Apalis I2C2 (DDC) */
&i2c0 {
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_lpi2c0>;
#address-cells = <1>;
#size-cells = <0>;
clock-frequency = <100000>;
status = "okay";
};
&hdmi {
ddc-i2c-bus = <&i2c0>;
status = "okay";
};
The “get-edid -b 2” app hangs without output and the i2cdtect -y 2 command gives a very strange output (with very slow response):
root@av2x:/# i2cdetect -y 2
0 1 2 3 4 5 6 7 8 9 a b c d e f
00: 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f
10: 10 11 12 13 14 15 16 17 18 19 1a 1b 1c 1d 1e 1f
20: 20 21 22 23 24 25 26 27 28 29 2a 2b 2c 2d 2e 2f
30: -- -- -- -- -- -- -- -- 38 39 3a 3b 3c 3d 3e 3f
40: 40 41 42 43 44 45 46 47 48 49 4a 4b 4c 4d 4e 4f
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
60: 60 61 62 63 64 65 66 67 68 69 6a 6b 6c 6d 6e 6f
70: 70 71 72 73 74 75 76 77
The rootfs is ubuntu 20.04 without any graphic support. The 205, 207 pins have pullup resistors at 3.3V and we use the HDMI2C1-14HDS for ESD protection. During the i2cdetect there is no activity at the I2C bus.
Do you have any advice?
Best Regards,
Giannis