Controlling gpio at early boot of wp7608

Legato Linux distribution (Yocto project)
1

Hi,

when we configure the GPIO21 using AT+WIOCFG to be high we find that the GPIO does not go high until late in the boot-up sequence. How can we get the GPIO to go high earlier in the boot e.g. In our case, we have simcard switch controlled by GPIO. we would like to control this gpio before the WP7608 has searched for the simcard

It seems to us that the WP7608 is pulling down the GPIO during the early boot up. Is this expected?
If so how can we change this behavior

Thanks,
Siva

2

Hi Siva,

Not sure your design and stage, is it possible to use hardware component to do so?
Or if you are modifying Yocto, you may consider to do this in Linux kernel or even bootloader to pull the pin early.

Thx

3

Hi,

I dont have access to bootloader. Can you point
How can I assign different bootargs in the bootloader ?

Thanks,
Siva

4

Hi Siva,

Are you rebuilding Yocto image?
If yes, please check code in yocto/lk or yocto/kernel folder on your build machine.
Reminded please be careful for any changes made as which may cause device abnormal.

Otherwise, a simple change (and test) is via init script to set the GPIO state on early boot, /etc/rcS.d/S08xx or /etc/rcS.d/S09xx could be a good place.

Hope it helps
Thx