Component Feature

• 32GB UFS
• Controller :
• TO

Failure Symptom

• fDeviceInit fail

Root Cause

GCBlkInfo: stored GC target Block information. (stored total one ItlvBlk#)
BitmapTbl: stored L2P information. (stored total user area’s ItlvBlk#)

• Pass Case

• Fail Case
• have found the unmatched table between GCBlkInfoand BitmapTbl, which are the cause of fDeviceInit fail.
• have found that unmatched table have been generated by the FW bug, which occurs under very complicated conditions.

Failure procedure

• Step1: GC starts at ItlvBlk#AAA
  • Failure occurrence condition (1)
  • The GC of IntlvBLK#AAAneeds to stop at the end page of the GC destination BLK just before Unmap.
• Step2 :ItlvBlk#Abecomes free group.
  • Failure occurrence condition (2)
  • ItlvBlk#AAAis unmapped, and ItlvBlk#AAA’snumber of valid data becomes zero, and Stop ItlvBlk#A’sGC
• Step3 : ItlvBlk#Ais assigned new block group.
  • Failure occurrence condition (3)
  • ItlvBlk#AAAshould be assigned new free blocks. In this case, ItlvBlk#AAAis selected from many free areas on BitmapTblby chance.

• Step4: GC starts at ItlvBlk#A

• Step5: As ItlvBlk#Ainfo between BitmapTbland GcBlkInfoare NOT the same, UFS device becomes fail because of unmatched table