IMX287 - Intenal pullup on an input GPIO pin didnt bring it to 3.3V

[thiagarajamural]

I am trying the pullup configuration of the pin GPIO2_16 in the IMX28 evaluation kit. This pin is named as SSP2_SCK in the EVK and it is not terminated, basically it is floating. I wrote a Linux driver and configured this pin as input and enabled the internal pullup. Following is the code extract of my driver,

#define GPIO_2_16               16

/*  Set GPIO2_16 as GPIO pin*/

__raw_writel(BF_PINCTRL_MUXSEL5_BANK2_PIN16(3), IO_ADDRESS(PINCTRL_PHYS_ADDR) + HW_PINCTRL_MUXSEL5_SET);

/* Set GPI02_16 as input*/

__raw_writel((1<<GPIO_2_16),IO_ADDRESS(PINCTRL_PHYS_ADDR) + HW_PINCTRL_DOE2_CLR);

/* Enable Pullup */

  __raw_writel((1<<GPIO_2_16),IO_ADDRESS(PINCTRL_PHYS_ADDR) + HW_PINCTRL_PULL2_SET);

After this I checked the voltage at the pin GPIO2_16, I am expecting to see the voltage of 3.3V since I enabled internal pullup.  But I see the voltage of 0V.  Am I wrong in assuming that the internal pullup should bring voltage to 3.3 V when that pin is floating? Or are any configurations are required to enable the internal pull up properly?

Thanks in advance

Murali

[CarlosCasillas]

Hi Murali,

Have you ensured that the drivers for other peripherals that share the same pin are configuring it in a different way? Additionally, have you checked if the proper power rail is configured and turned on?

On this link you could find a pin control driver for the i.MX28, and on this one you could find application note AN4199, which talks about the Power Management of the i.MX28.

Hope this will be useful for you.
Best regards!
/Carlos

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[thiagarajamural]

Hi Carlos,

I am using the prebuilt Linux kernel image of IMX28 available in the MFG tool for IMX287 development board. I only loaded my driver to configure the mentioned GPIO without changing any of the underlying system. I assume the power rail should be configured properly in the prebuilt image. Anyway I'll double check on power rail and also try use the pin control driver to further test on this.

Thanks

Murali