[U-Boot] Device hung at stack pointer

Hey guys!
My device got hung after a power cycle at stack pointer and is irreversible now.
Can someone let me know the possibilities which could have lead to such hungs ?

I could find the RAM inflation stopped at 4MB is issue scenario, while it should have been 128 MB

Issue scenario:

U-Boot 1.1.4-g7ece510f-dirty (Aug 16 2018 - 13:28:18)
 
ap151 - Dragonfly 1.0DRAM:
sri
ath_ddr_initial_config(278): (ddr2 init)
ath_sys_frequency: cpu 775 ddr 650 ahb 258
Tap values = (0x8, 0x8, 0x8, 0x8)
4 MB
Top of RAM usable for U-Boot at: 80400000
Reserving 218k for U-Boot at: 803c8000
Reserving 192k for malloc() at: 80398000
Reserving 44 Bytes for Board Info at: 80397fd4
Reserving 36 Bytes for Global Data at: 80397fb0
Reserving 128k for boot params() at: 80377fb0
Stack Pointer at: 80377f98

Working scenario:

U-Boot 1.1.4-g7ece510f-dirty (Aug 16 2018 - 13:28:18)
 
ap151 - Dragonfly 1.0DRAM:
sri
ath_ddr_initial_config(278): (ddr2 init)
ath_sys_frequency: cpu 775 ddr 650 ahb 258
Tap values = (0x10, 0x10, 0x10, 0x10)
128 MB
Top of RAM usable for U-Boot at: 88000000
Reserving 218k for U-Boot at: 87fc8000
Reserving 192k for malloc() at: 87f98000
Reserving 44 Bytes for Board Info at: 87f97fd4
Reserving 36 Bytes for Global Data at: 87f97fb0
Reserving 128k for boot params() at: 87f77fb0
Stack Pointer at: 87f77f98
Now running in RAM - U-Boot at: 87fc8000
Flash Manuf Id 0xef, DeviceId0 0x40, DeviceId1 0x18
flash size 16MB, sector count = 256
Flash: 16 MB
Power up PLL with outdiv = 0 then switch to 3
In:    serial
Out:   serial
Err:   serial
Net:   ath_gmac_enet_initialize...

I'm really eager to know the reason!
Thanks in advance!