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4.7BurstPriorityRegister(BPRIO)
DDR2MemoryControllerRegisters
TheBurstPriorityRegister(BPRIO)helpspreventcommandstarvationwithintheDDR2memory
controller.Toavoidcommandstarvation,theDDR2memorycontrollermomentarilyraisesthepriorityof
theoldestcommandinthecommandFIFOafterasetnumberoftransfershavebeenmade.The
PRIO_RAISEbitsetsthenumberoftransfersthatmustbemadebeforetheDDR2memorycontroller
raisesthepriorityoftheoldestcommand.TheBPRIOisshowninFigure26anddescribedinTable24.
SeeSection2.7.2formoredetailsoncommandstarvation.
Figure26.BurstPriorityRegister(BPRIO)
3116
Reserved
R-0
15870
ReservedPRIO_RAISE
R-0R/W-0xFF
LEGEND:R/W=Read/Write;R=Readonly;-n=valueafterreset
Table24.BurstPriorityRegister(BPRIO)FieldDescriptions
BitFieldValueDescription
31-8ReservedReserved.Thereservedbitlocationisalwaysreadas0.Avaluewrittentothisfieldhasnoeffect.
7-0PRIO_RAISENumberofmemorytransfersafterwhichtheDDR2memorycontrollerwillelevatethepriorityofthe
oldestcommandinthecommandFIFO.SettingthisfieldtoFFhdisablesthisfeature,thereby
allowingoldcommandstostayintheFIFOindefinitely.
01memorytransfer
12memorytransfers
23memorytransfers
3-FEh4-FFhmemorytransfers
FFhFeaturedisabled,commandscanstayincommandFIFOindefinitely
44DSPDDR2MemoryControllerSPRUEK5A–October2007
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