Failed to set core voltage! Can't set CPU frequency

Hello All,

Does someone knows a possible reason why AXP 209 on some boards are failing?

That will result to an error message "Failed to set core voltage! Can't set CPU frequency".

After that we cannot probe the i2c bus address of the AXP209 anymore.

Hope someone can share some insights.

U-Boot SPL 2015.10-rc5-gc387326-dirty (May 19 2016 - 19:02:38)                  
DRAM: 1024 MiB                                                                  
Failed to set core voltage! Can't set CPU frequency                             
Card did not respond to voltage select!                                         
                                                                                
                                                                                
U-Boot 2015.10-rc5-gc387326-dirty (May 19 2016 - 19:02:38 +0800) Allwinner Techy
                                                                                
CPU:   Allwinner A20 (SUN7I)                                                    
I2C:   ready                                                                    
DRAM:  1 GiB                                                                    
MMC:   Card did not respond to voltage select!                                  
SUNXI SD/MMC: 1, SUNXI SD/MMC: 0 (eMMC)                                         
In:    serial                                                                   
Out:   serial                                                                   
Err:   serial                                                                   
SCSI:  SUNXI SCSI INIT                                                          
AHCI PHY power up failed.                                                       
Net:   No ethernet found.                                                       
starting USB...                                                                 
USB0:   USB EHCI 1.00                                                           
USB1:   USB OHCI 1.0                                                            
USB2:   USB EHCI 1.00                                                           
USB3:   USB OHCI 1.0                                                            
scanning bus 0 for devices... 1 USB Device(s) found                             
scanning bus 2 for devices... 2 USB Device(s) found                             
Hit any key to stop autoboot:  0

Thanks in advance...