2.16.1.4StatisticsInterrupt
2.16.1.5HostErrorInterrupt
Architecture
TheEMACwritetothecompletionpointeractuallystoresthevalueinthestateRAM.TheCPUwritten
valuedoesnotactuallychangetheregistervalue.Thehostwrittenvalueiscomparedtotheregister
content(whichwaswrittenbytheEMAC)andifthetwovaluesareequalthentheinterruptisremoved;
otherwise,theinterruptremainsasserted.Thehostmayprocessmultiplepacketspriorto
acknowledginganinterrupt,orthehostmayacknowledgeinterruptsforeverypacket.
Thestatisticslevelinterrupt(STATPEND)isissuedwhenanystatisticsvalueisgreaterthanorequalto
80000000h,ifenabledbysettingtheSTATMASKbitintheMACinterruptmasksetregister
(MACINTMASKSET)to1.Thestatisticsinterruptisremovedbywritingtodecrementanystatistics
valuegreaterthan80000000h.Aslongasthemost-significantbitofanystatisticsvalueisset,the
interruptremainsasserted.
Thehosterrorinterrupt(HOSTPEND)isissued,ifenabled,undererrorconditionsdealingwiththe
handlingofbufferdescriptors,detectedduringtransmitorreceiveDMAtransactions.Thefailureofthe
softwareapplicationtosupplyproperlyformattedbufferdescriptorsresultsinthiserror.Theerrorbit
canonlybeclearedbyresettingtheEMACmoduleinhardware.
ThehosterrorinterruptisenabledbysettingtheHOSTMASKbitintheMACinterruptmasksetregister
(MACINTMASKSET)to1.ThehosterrorinterruptisdisabledbyclearingtheappropriatebitintheMAC
interruptmaskclearregister(MACINTMASKCLEAR)to0.Therawandmaskedhosterrorinterrupt
statusmaybereadbyreadingtheMACinterruptstatus(unmasked)register(MACINTSTATRAW)and
theMACinterruptstatus(masked)register(MACINTSTATMASKED),respectively.
Thetransmithosterrorconditionsare:
•SOPerror
•OwnershipbitnotsetinSOPbuffer
•ZeronextbufferdescriptorpointerwithEOP
•Zerobufferpointer
•Zerobufferlength
•Packetlengtherror
Thereceivehosterrorconditionsare:
•Ownershipbitnotsetininputbuffer
•Zerobufferpointer
EthernetMediaAccessController(EMAC)/ManagementDataInput/Output(MDIO) 58SPRUEQ6–December2007
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