How to prevent i.MX6 I2C communication to MMPF0100 after boot.

[satoshishimoda]

Hi community,

I want to know how to stop I2C communication from i.MX6 to MMPF0100 after boot.
I know sometimes i.MX6 communicate with MMPF0100 by I2C automatically after boot.
However, rarely this communication cuase a problem on a custom board.
So we want to use I2C communication to MMPF0100 when only u-boot works for changing MMPF0100 output voltage.
In other words, we want to prevent I2C communication to MMPF0100 after Linux kernel is booted.
Could you let me know how to do it?

Best Regards,
Satoshi Shimoda

[AnsonHuang]

I think you can just build out PFuse driver in kernel. Not sure which kernel you are running, there are several ways of build out a module.

[satoshishimoda]

Hi Yongcai Huang,

Thank you for your quick response, and sorry my short infromation.

We are using Android BSP (jb_4.2.2_1.0.0), so kernel is L3.0.35_4.1.0.

> I think you can just build out PFuse driver in kernel.

I consider the i2c communicatoin is controled by kernel_imx/drivers/mfd/pfuze-core.c.

So I can do it by modification the file, right?

To make sure, I want to confirm whether we can use low power mode even if we will modify the file.

I think we can use low power mode because low power mode is controled by Low-level Power Management (PM) Driver and it does not use I2C communication.

Is this right?

Best Regards,

Satoshi Shimoda

[AnsonHuang · Accepted solution]

I think you can just remove the registry of pmic driver in arch/arm/mach-mx6/mx6q_sabresd_pmic_pfuze100.c mx6q_sabresd_init_pfuze100().

Yes, it should not impact low power mode, but you need to config PMIC's standby voltage correctly in uboot, just refer to the initializtion in pfuze100_init routine.