I2C device getting detected in kernel but not in u-boot stage

Hi Nvidia team,

I am using I2C to GPIO expander in i2c bus 7(as per kernel).When i check i2c probe in u-boot stage i am not able to detect the same device.

Attaching the logs taken after kernel bootup and uboot stage,

U-boot stage:
Tegra186 (P3636-0001) # i2c dev 6
Setting bus to 6
Tegra186 (P3636-0001) # i2c probe
Valid chip addresses: 18 50

After Kernel bootup:

root@tegra-ubuntu:/home/ubuntu# i2cdetect -r -y 7
0 1 2 3 4 5 6 7 8 9 a b c d e f
00: – – – – – – – – – – – – –
10: – – – – – – – – UU – – – – – – –
20: – – UU – – – – – – – – – – – – –
30: – – – – – – – – – – – – – – – –
40: – – – – – – – – – – – – – – – –
50: 50 – – – – – – – – – – – – – – –
60: – – – – – – – – – – – – – – – –
70: UU – – – – – – –

Can you please let me know what can be the issue here?

Thanks

hello prasanth.gunaseelan,

may I know what’s the actual use-case for detecting that during u-boot?

Hi Jerry,

We are connecting power enable pins for modem to this device(IO expander) and controlling it in u-boot stage to boot the modem before TX2 boots up.

So we need to access the device in the u-boot stage.

Hi jerry,

Can you let me know if there is any update on this issue?

Hi Jerry,

Can you please give us an update on the issue?

Thanks

TCA6424’s power comes from vcc_1v8.
Please confirm the confirm TCA6424’s power at u-boot stage.

Hi kayccc,

We are getting vcc_1v8 and it is out of reset at the uboot stage.

Still it is not getting detected.

Hi kayccc,

Any update on the observation we saw?

hello prasanth.gunaseelan,

could you please check waveform via oscilloscope,
please connect TCA6424 {sda, scl} pins to oscilloscope to check if ACK is send by TCA6424.
thanks

There is no update from you for a period, assuming this is not an issue any more.
Hence we are closing this topic. If need further support, please open a new one.
Thanks

Hi prasanth.gunaseelan,

Any update/result can be shared?