RTC not working in imx6ul

[pratyushtomar]

We have a custom board based on imx6ul evk board and we are using internal RTC with backup battery attached to VDD_SNVS_IN. Our problem is that RTC doesn't work after shutdown when we enable following settings in our kernel

CONFIG_POWER_RESET=y

CONFIG_POWER_RESET_SYSCON_POWEROFF=y

But if we disable these settings then RTC works normally but our board consumes power even after proper shutdown since these settings are disabled in defconfig and .config file.

Thus, how can we resolve this situation and what is the reason for rtc not working when above mentioned settings are enabled in kernel?

[Yuri]

Hello,

  There is the SNVS issue from Errata : ERR010690 SNVS: SNVS_LP Registers Reset Issue
Look at the recent Errata for more details.

 http://www.nxp.com/assets/documents/data/en/errata/IMX6ULCE.pdf

Regards,

Yuri.

[pratyushtomar]

I checked the errata document and found that both workaround mentioned are already there, we are using VDD_HIGH_IN = 2.8 V and    VDD_HIGH_IN powered up before VDD_SOC_IN and in inverted order while shutdown.

So I think the power sequencing is correct. What else can be done to solve RTC problem?

[Yuri]

Hello, 

VDD_HIGH_IN power down is earlier than VDD_SOC_IN - is it Your case ?

Let's look at VDD_HIGH_IN and  VDD_SOC_IN power down waveforms.

Regards,

Yuri.

[pratyushtomar]

Yes VDD_HIGH_IN power down is earlier than VDD_SOC_IN

[Yuri]

Hello,

   From section 27.3.2 (Menu Configuration Options) of the recent BSP i.MX Linux Reference

Manual.

   To get to the SRTC driver, use the command bitbake linux-imx -c menuconfig. On the
screen displayed, select Configure the kernel and exit. When the next screen appears
select the following options to enable the SRTC driver:

• Device Drivers > Real Time Clock > Freescale SNVS Real Time Clock

Have You tried it ?

Regards,

Yuri.

[pratyushtomar]

I checked using bitbake linux-imx -c menuconfig and Freescale SNVS Real Time Clock support is already enabled in our kernel.

[Yuri]

Hello,

  Please create request (ticket) and provide the schematic for review.

http://www.nxp.com/support/sales-and-support:SUPPORTHOME 

Regards,

Yuri.