May 17, 20001. 2 USB 2.0 Hub Details John Garney Hub Working Group Chair Intel Corporation John Garney Hub Working Group Chair Intel Corporation

May 17, 2000 1

May 17, 2000 2

USB 2.0 Hub Details

USB 2.0 Hub Details

John GarneyJohn GarneyHub Working Group ChairHub Working Group Chair

Intel CorporationIntel Corporation

John GarneyJohn GarneyHub Working Group ChairHub Working Group Chair

Intel CorporationIntel Corporation

May 17, 2000 3

Hub DetailsHub Details

Standard Hub ClassStandard Hub Class– Port IndicatorsPort Indicators

Transaction TranslatorTransaction Translator Bulk/Control Transaction HandlingBulk/Control Transaction Handling Isochronous/Interrupt Transaction HandlingIsochronous/Interrupt Transaction Handling Scheduling Split TransactionsScheduling Split Transactions

Additions to Chapter 11Additions to Chapter 11 New AppendicesNew Appendices

May 17, 2000 4

Hub Requirements:Hub Requirements:

Isolate full/low-speed from high-speedIsolate full/low-speed from high-speed– Avoid lower speed impact on HS, i.e., LS impact on FSAvoid lower speed impact on HS, i.e., LS impact on FS

All USB2.0 Hub ports support HS/FS/LSAll USB2.0 Hub ports support HS/FS/LS

May 17, 2000 5

Standard Hub ClassStandard Hub Class

Hub DescriptorHub Descriptor– Added to Added to wHubCharacteristicswHubCharacteristics::

D6..D5: TT Think TimeD6..D5: TT Think Time D7: Port indicator supportD7: Port indicator support

Hub Class RequestsHub Class Requests– New Port Features: PORT_TEST, PORT_INDICATORNew Port Features: PORT_TEST, PORT_INDICATOR– Get_Status: PORT_HIGH_SPEEDGet_Status: PORT_HIGH_SPEED– New: ClearTTBuffer, ResetTT, GetTTState, StopTTNew: ClearTTBuffer, ResetTT, GetTTState, StopTT

May 17, 2000 6

Hub Port IndicatorsHub Port Indicators

OptionalOptional standardized end user visible indicator standardized end user visible indicator 2 color indicator for each downstream facing port2 color indicator for each downstream facing port

– Defined colors: Off, Green, Amber, BlinkingDefined colors: Off, Green, Amber, Blinking Manual (Host SW) & Automatic ControlManual (Host SW) & Automatic Control

– Manual: keeps HW simple while allowing SW controlManual: keeps HW simple while allowing SW control Blinking done by softwareBlinking done by software

– Automatic: basic consistency in USB 1.x/2.0 systemsAutomatic: basic consistency in USB 1.x/2.0 systems Overcurrent, enabled and “neither”Overcurrent, enabled and “neither”

– Full indicator support requires USB 2.0 softwareFull indicator support requires USB 2.0 software

May 17, 2000 7

ColorColor DefinitionDefinitionOffOff Not OperationalNot Operational

AmberAmber Error ConditionError Condition

GreenGreen Fully OperationalFully Operational

Blinking Off/GreenBlinking Off/Green Software AttentionSoftware Attention

Blinking Off/AmberBlinking Off/Amber Hardware AttentionHardware Attention

Blinking Amber/GreenBlinking Amber/Green ReservedReserved

Indicator Color MeaningsIndicator Color Meanings

May 17, 2000 8

Indicator ControlIndicator Control

Controlled via SetPortFeature(PORT_INDICATOR, indicator_selector)Controlled via SetPortFeature(PORT_INDICATOR, indicator_selector)

ValueValue Port Indicator SelectorPort Indicator Selector Port Indicator Port Indicator ModeMode

Color set automatically, as Color set automatically, as defined in followingdefined in following

AutomaticAutomatic

11 AmberAmber ManualManual

22 GreenGreen

33 OffOff

4-FFH4-FFH ReservedReserved ReservedReserved

00

May 17, 2000 9

Automatic Indicator ControlAutomatic Indicator Control

SetPortFeature(SetPortFeature(PORT_POWER)PORT_POWER)

AutomaticAutomatic ModeMode

OffOffOffOff!(Enabled or Transmit or TransmitR)!(Enabled or Transmit or TransmitR)

and PORT_OVER_CURRENT != 1and PORT_OVER_CURRENT != 1

Enabled or Transmit or TransmitREnabled or Transmit or TransmitR

GreenGreenGreenGreen

SetPortFeature(SetPortFeature(PORT_INDICATOR,PORT_INDICATOR,

indicator_selector = 0)indicator_selector = 0)

SetPortFeature(SetPortFeature(PORT_INDICATOR,PORT_INDICATOR,

indicator_selector != 0)indicator_selector != 0)

ManualManualModeMode

AmberAmber

PORT_OVER_CURRENT = 1PORT_OVER_CURRENT = 1

May 17, 2000 10

Host Controller / TT InteractionsHost Controller / TT Interactions

HostHostHostHost

DeviceDeviceDeviceDevice

TTTTTTTTXX22

TT buffers full/low speed transaction information (X) locallyTT buffers full/low speed transaction information (X) locally

1 – SPLIT-s, OUT, DATAx1 – SPLIT-s, OUT, DATAx(Start-split)(Start-split)

Host Controller issues start-split transaction to TTHost Controller issues start-split transaction to TT

TTTTTTTT RR

4 - ...,ACK4 - ...,ACK

TT buffers full/low speed transaction results (R) locallyTT buffers full/low speed transaction results (R) locally

3 - OUT, DATAx, ...3 - OUT, DATAx, ...

TT issues full/low speed transaction on downstream busTT issues full/low speed transaction on downstream bus

6 - …,ACK6 - …,ACK

TT responds with resultsTT responds with results

InterruptInterruptOutOut

ExampleExample

5 – SPLIT-c, OUT, …5 – SPLIT-c, OUT, …(Complete-split)(Complete-split)

Host Controller issues complete-split transaction to TTHost Controller issues complete-split transaction to TT

May 17, 2000 11

Transaction Translator Overview Transaction Translator Overview

Bulk/Control & Interrupt/Isochronous portions to TTBulk/Control & Interrupt/Isochronous portions to TT– Bulk/Control uses USB flow control to make progressBulk/Control uses USB flow control to make progress– Interrupt/Isochronous uses a scheduled full/low speedInterrupt/Isochronous uses a scheduled full/low speed

transaction “pipeline”transaction “pipeline”– Separate buffers are used for each TT portionSeparate buffers are used for each TT portion

2 or more transaction buffers for bulk/control2 or more transaction buffers for bulk/control Start & complete “pipeline” buffers for interrupt/isochronousStart & complete “pipeline” buffers for interrupt/isochronous

Transaction TranslatorTransaction TranslatorTransaction TranslatorTransaction Translator

Bulk &ControlBulk &Control

Interrupt &IsochronousInterrupt &

Isochronous

May 17, 2000 12

Example: Bulk OUTSingle Split Trans.Example: Bulk OUTSingle Split Trans.

TTTTTTTT

X22

TT buffers full/low speed transaction information (X) locallyTT buffers full/low speed transaction information (X) locally


TT issues full/low speed transaction on downstream busTT issues full/low speed transaction on downstream bus

RR

4 - ...,ACK4 - ...,ACK4 - ...,ACK4 - ...,ACK

TT buffers full/low speed transaction results (R) locallyTT buffers full/low speed transaction results (R) locally TT buffers full/low speed transaction results (R) locallyTT buffers full/low speed transaction results (R) locally

6 - …,ACK6 - …,ACK

TT responds with resultsTT responds with results

1 – SPLIT-s, OUT, DATAx, ACK1 – SPLIT-s, OUT, DATAx, ACK1 – SPLIT-s, OUT, DATAx, ACK1 – SPLIT-s, OUT, DATAx, ACK

Host Controller issues start-split transaction to TTHost Controller issues start-split transaction to TT Host Controller issues start-split transaction to TTHost Controller issues start-split transaction to TT

5 – SPLIT-c, OUT, ...5 – SPLIT-c, OUT, ...5 – SPLIT-c, OUT, ...5 – SPLIT-c, OUT, ...

Host Controller issues complete-split transaction to TTHost Controller issues complete-split transaction to TT Host Controller issues complete-split transaction to TTHost Controller issues complete-split transaction to TT

May 17, 2000 13

Example Bulk OUT SplitsExample Bulk OUT Splits

Assume 2 classic bulk OUT endpointsAssume 2 classic bulk OUT endpoints Assume 1 TT bulk/control bufferAssume 1 TT bulk/control buffer

HS Bus:HS Bus:

Classic Bus:Classic Bus:

SS

SS2aSS2a

OO DD NNSS

SS1aSS1a

OO DD AA

FullFull

SS2aSS2a

OO DD NNSS

CS1aCS1a

OO YYCC

ReadyReady

SS2aSS2a

OO DD AASS

FullFull

CS1aCS1a

OO AACC

EmptyEmpty

Periodic XactsPeriodic Xacts

EmptyEmptyTT Bulk Buffer:TT Bulk Buffer:

CS2aCS2a

OO YYCC

TIMETIME

OO DD AA

EP1 Transaction EP1 Transaction

OO D …D …


May 17, 2000 14

Example: Bulk OUTTwo Different Split Trans.Example: Bulk OUTTwo Different Split Trans.

TTTTTTTT

X22


RR

6 - ...,ACK6 - ...,ACK6 - ...,ACK6 - ...,ACK

TT buffers 1st full/low speed transaction results (R) locallyTT buffers 1st full/low speed transaction results (R) locally

1 – SPLIT-s, OUT, DATAx, ACK1 – SPLIT-s, OUT, DATAx, ACK1 – SPLIT-s, OUT, DATAx, ACK1 – SPLIT-s, OUT, DATAx, ACK

- Same as before- Same as before- Same as before- Same as before HC issues Start-split transaction for different endpoint to TTHC issues Start-split transaction for different endpoint to TT HC issues Start-split transaction for different endpoint to TTHC issues Start-split transaction for different endpoint to TT

4 – SPLIT-c, OUT, DATAx, ACK4 – SPLIT-c, OUT, DATAx, ACK4 – SPLIT-c, OUT, DATAx, ACK4 – SPLIT-c, OUT, DATAx, ACK

x2

TT buffers full/low speed transaction (x2) locally in 2nd bufferTT buffers full/low speed transaction (x2) locally in 2nd buffer TT buffers full/low speed transaction (x2) locally in 2nd bufferTT buffers full/low speed transaction (x2) locally in 2nd buffer

55

TT issues 2nd full/low speed transaction on downstream busTT issues 2nd full/low speed transaction on downstream bus TT issues 2nd full/low speed transaction on downstream busTT issues 2nd full/low speed transaction on downstream bus


May 17, 2000 15

Example: Bulk OUTTwo Different Split Trans.Example: Bulk OUTTwo Different Split Trans.

TTTTTTTT

TT responds with results from 1st bufferTT responds with results from 1st buffer TT responds with results from 1st bufferTT responds with results from 1st buffer

9 - …,ACK9 - …,ACK

HC issues complete-split transaction for 2nd endpoint to TTHC issues complete-split transaction for 2nd endpoint to TT HC issues complete-split transaction for 2nd endpoint to TTHC issues complete-split transaction for 2nd endpoint to TT

8 – SPLIT-s, OUT, ... 8 – SPLIT-s, OUT, ... 8 – SPLIT-s, OUT, ... 8 – SPLIT-s, OUT, ...

r2r2

10 TT buffers full/low speed transaction results (r2) locallyTT buffers full/low speed transaction results (r2) locally TT buffers full/low speed transaction results (r2) locallyTT buffers full/low speed transaction results (r2) locally

10 - ...,ACK10 - ...,ACK10 - ...,ACK10 - ...,ACK

RR

12 TT responds with resultsTT responds with results

12 - …,ACK12 - …,ACK

11 HC issues complete-split transaction for 2nd endpoint to TTHC issues complete-split transaction for 2nd endpoint to TT HC issues complete-split transaction for 2nd endpoint to TTHC issues complete-split transaction for 2nd endpoint to TT

11 – SPLIT-c, OUT, ...11 – SPLIT-c, OUT, ... 11 – SPLIT-c, OUT, ...11 – SPLIT-c, OUT, ...

May 17, 2000 16

Example Bulk OUT SplitsExample Bulk OUT Splits

Assume 2 classic bulk OUT endpointsAssume 2 classic bulk OUT endpoints Always at least 2 TT bulk/control buffersAlways at least 2 TT bulk/control buffers

HS Bus:HS Bus:

Classic Bus:Classic Bus:

SS

SS1aSS1a

OO DD AA

1 Full1 Full1 Empty1 Empty

Periodic XactsPeriodic Xacts

1 Ready1 Ready

CS1aCS1a

OO YYCC

1 Empty1 Empty

CS1aCS1a

OO AACC

SS1bSS1b

OO DD AASS

1 Full1 FullTT Bulk Buffer:TT Bulk Buffer:

CS2aCS2a

OO YYCC

TIMETIME

OO D …D …OO DD AA


OO DD AA


SS

SS2aSS2a

OO DD AA

2 Full2 Full

CS2aCS2a

OO YYCC

2 Ready2 Ready

May 17, 2000 17

TT Int. / Isoch. PipelineTT Int. / Isoch. Pipeline

Host software budgets when full/low-speed transaction will runHost software budgets when full/low-speed transaction will run Host schedules start-split before “earliest” start timeHost schedules start-split before “earliest” start time Host schedules complete-split at “latest” finish time(s)Host schedules complete-split at “latest” finish time(s) Scheduling accounts for variation due to bit-stuffingScheduling accounts for variation due to bit-stuffing

and timeouts, etc.and timeouts, etc.

TTTTTTTT

High Speed Start-SplitHigh Speed Start-Split High Speed Complete-SplitHigh Speed Complete-Split

Start-splitStart-splitFIFOFIFO


Complete-splitComplete-splitFIFOFIFO


StartStartHandlerHandler


CompleteCompleteHandlerHandler


Full/LowFull/LowHandlerHandlerFull/LowFull/LowHandlerHandler

May 17, 2000 18

TTTTTTTT





Full/LowFull/LowHandlerHandlerFull/LowFull/LowHandlerHandler





XX22

TT buffers full/low speed transaction information locally

1 – SPLIT-s, OUT, DATAx1 – SPLIT-s, OUT, DATAx

Host Controller issues start-split transaction to TT


TT issues full/low speed transaction on downstream bus

5 – SPLIT-c, OUT, ...5 – SPLIT-c, OUT, ...

Host Controller issues complete-split transaction to TT

6 - …,ACK6 - …,ACK

TT responds with results

Example: Int. OUT Split Trans.Example: Int. OUT Split Trans.

RR

4 - ...,ACK4 - ...,ACK

TT buffers full/low speed transaction results locally



May 17, 2000 19

Scheduling TT PipelineScheduling TT Pipeline

Best case budget & worst case operationBest case budget & worst case operation Scheduling split transactions for pipelineScheduling split transactions for pipeline Keeping the pipeline runningKeeping the pipeline running

May 17, 2000 20

Best Full-Speed BudgetBest Full-Speed Budget

Max. 1500 bytes per classic frame (12Mb/s)Max. 1500 bytes per classic frame (12Mb/s) Max. 1350 bytes of periodic wire time (90% of frame)Max. 1350 bytes of periodic wire time (90% of frame) Max. 1157 allocatable bytes w/ max 6/7 (16.67%) bit stuffMax. 1157 allocatable bytes w/ max 6/7 (16.67%) bit stuff

– Reduced further by other overheadReduced further by other overhead Max. 187.5 “wire” bytes per 125us microframeMax. 187.5 “wire” bytes per 125us microframe

– Budget best case of 188 bytesBudget best case of 188 bytes Best Case Budget assumes wire runs “as fast as possible”Best Case Budget assumes wire runs “as fast as possible”

YY00 YY11 YY22 YY33 YY44 YY55 YY66 YY77

2929188 188 188 188 188 188

3232187.5 187.5 187.5 187.5 187.5 187.5

MicroframesMicroframes

Best case wireBest case wirebudget,1157 bytes budget,1157 bytes w/ no bitstuffingw/ no bitstuffing

Max wire timeMax wire time

May 17, 2000 21

Worst Case OperationWorst Case Operation

Worst case when bus runs “as slow as possible”Worst case when bus runs “as slow as possible” 188 “data” bytes can take 220 bytes of time to move188 “data” bytes can take 220 bytes of time to move Classic transaction runs in three possible microframesClassic transaction runs in three possible microframes

– Due to difference between best & worst caseDue to difference between best & worst case

YY00 YY11 YY22 YY33 YY44 YY55 YY66 YY77

Best case wireBest case wirebudget, 1157 bytes budget, 1157 bytes w/ no bitstuffingw/ no bitstuffing

2929188 188 188 188 188 188

MicroframesMicroframes

220 219 219 220 219 219 34Worst case,Worst case,1350 bytes1350 bytesw/ max bitstuffingw/ max bitstuffing

161161161161187Worst caseWorst casewith bulk reclaimwith bulk reclaim 219 219 220 219 219 34

162 bytes162 bytes

Reclamation (LS control) makes it no worseReclamation (LS control) makes it no worse

May 17, 2000 22

Transaction SchedulingTransaction Scheduling

Classic transaction determines HS split-transactionsClassic transaction determines HS split-transactions Allocate time on classic wire for a new transaction:Allocate time on classic wire for a new transaction:

– Calculate best case classic wire budgetCalculate best case classic wire budget Determine schedule for high speed start-split(s)Determine schedule for high speed start-split(s)

– Based on Best case budgetBased on Best case budget Determine schedule for high speed complete-split(s)Determine schedule for high speed complete-split(s)

– Based on Best case budget and rules that deal with worstBased on Best case budget and rules that deal with worst– Don’t compute worst case, use “3” microframesDon’t compute worst case, use “3” microframes

May 17, 2000 23

Generic Scheduling of Split TransactionsGeneric Scheduling of Split Transactions

Allocate time for a new transactionAllocate time for a new transaction

(Y-1)(Y-1)77 YY00 YY11 YY22 YY33 YY44 YY55 YY66 YY77

Best case budgetBest case budget

#1: A classic transaction budgeted #1: A classic transaction budgeted to run here on the classic bus,...to run here on the classic bus,...

#2: …has a HS start-split scheduled#2: …has a HS start-split scheduledin this microframe and ...in this microframe and ...#2: …has a HS start-split scheduled#2: …has a HS start-split scheduledin this microframe and ...in this microframe and ...

HSHSStart-splitStart-splitHSHSStart-splitStart-split

Start-splits scheduled in microframe “before” Best case classicStart-splits scheduled in microframe “before” Best case classic Start-splits scheduled in microframe “before” Best case classicStart-splits scheduled in microframe “before” Best case classic

Additional scheduling rules for specific cases (see chap 11)Additional scheduling rules for specific cases (see chap 11) Complete-splits in (roughly) “next 3” microframesComplete-splits in (roughly) “next 3” microframes

#3: …has HS complete-split transactions#3: …has HS complete-split transactionsscheduled in the latest possible microframes scheduled in the latest possible microframes for this transactionfor this transaction

HS Complete-splitsHS Complete-splits

May 17, 2000 24

Long Isochronous OUTLong Isochronous OUT

Isochronous OUT with >188 data payload has:Isochronous OUT with >188 data payload has:– More start-splitsMore start-splits

A start-split for each microframe with budgeted data presentA start-split for each microframe with budgeted data present Different PID based on which portion of classic data (begin,mid,end)Different PID based on which portion of classic data (begin,mid,end) Each start-split is scheduled 188 data bytes (except last)Each start-split is scheduled 188 data bytes (except last)

– No complete-split(s)No complete-split(s)

(Y-1)(Y-1)77 YY00 YY11 YY22 YY33 YY44 YY55 YY66 YY77

BeginBegin EndEndMidMid MidMid

Best case budgetBest case budget

Microframes with HS Start-SplitsMicroframes with HS Start-Splits

Long isoch. transactionLong isoch. transaction

Start-SplitStart-SplitTokens:Tokens:

May 17, 2000 25

Keeping the Pipe RunningKeeping the Pipe Running

TT periodic pipeline must continue to sequenceTT periodic pipeline must continue to sequence– Normally it does, but…Normally it does, but…– Errors can occur on high/full/low-speed busesErrors can occur on high/full/low-speed buses

TT must not service full/low-speed transactions:TT must not service full/low-speed transactions:– Too earlyToo early– Too lateToo late

Microframe “clock” tracking is requiredMicroframe “clock” tracking is required

May 17, 2000 26

Periodic Pipeline ExamplePeriodic Pipeline Example

Example full speed transactions:Example full speed transactions:– T1: 187 data byte isoch INT1: 187 data byte isoch IN– T2: 376 data byte isoch OUTT2: 376 data byte isoch OUT– T3: 188 data byte isoch INT3: 188 data byte isoch IN– T4: 564 data byte isoch INT4: 564 data byte isoch IN

Schedule start-splitsSchedule start-splits

SSx SSx - Start-splits- Start-splitsTx - Classic transactionTx - Classic transactionCSx - Complete-splitsCSx - Complete-splits

Best Budget:Best Budget: T3T3T1T1 T2T2 T4T4

SS3SS3SS1SS1 SS4SS4SS2aSS2a SS2cSS2cSS2bSS2b

May 17, 2000 27

Pipeline ExamplePipeline Example

Schedule Complete-splitsSchedule Complete-splitsSSx - Start-splitsSSx - Start-splitsTx - Classic transactionTx - Classic transactionCSxCSx - Complete-splits - Complete-splits

Best Budget:Best Budget: T1T1 T2T2 T4T4T3T3

CS3bCS3bCS3aCS3a CS3cCS3cCS1aCS1a CS1bCS1b CS1cCS1c CS4bCS4b CS4dCS4dCS4cCS4cCS4aCS4a

– Isoch OUT T2 has no complete-splitsIsoch OUT T2 has no complete-splits– Isoch IN T4 only has one additional complete-splitIsoch IN T4 only has one additional complete-split

May 17, 2000 28

SS2bSS2b SS2cSS2c SS3SS3 SS4aSS4a

CS1bCS1b

data0data0

CS3aCS3a

errerr

CS4aCS4a

mdatamdata

CS1aCS1a

mdatamdataTT Response:TT Response:

Actual:Actual:

SSxSSx - Start-splits - Start-splitsTx - Classic transactionTx - Classic transactionCSxCSx - Complete-splits - Complete-splits

CS4bCS4b

mdatamdata

CS4cCS4c

mdatamdata

CS4dCS4d

data0data0

Periodic Pipeline ExamplePeriodic Pipeline Example

T1T1 T2T2

Best Budget:Best Budget:

Worst Budget: Worst Budget: T3T3

T1T1 T2T2 T4T4T3T3

T4T4CS1aCS1a CS3bCS3b CS4bCS4b CS4dCS4dCS1bCS1b CS3aCS3a CS4aCS4a CS4cCS4cSS1SS1 SS2aSS2a SS2cSS2c SS3SS3 SS4aSS4aSS2bSS2b

SS1SS1 SS2aSS2a

T1T1T1T1 T2 T2 T2T2T2T2 BulkBulk T4 T4 T4T4T4T4T4T4

CS3cCS3c

May 17, 2000 29

Example Bus TracesExample Bus Traces

Split BulkSplit Bulk Split InterruptSplit Interrupt Split IsochronousSplit Isochronous

May 17, 2000 30

USB2.0 HubAdditions SummaryUSB2.0 HubAdditions Summary

Hub Class Descriptor & RequestsHub Class Descriptor & Requests Optional Standardized Port IndicatorsOptional Standardized Port Indicators TT InternalsTT Internals

– Bulk/Control bufferingBulk/Control buffering– Interrupt/Isochronous scheduled pipelineInterrupt/Isochronous scheduled pipeline

Host OS Microframe Pipeline SchedulingHost OS Microframe Pipeline Scheduling

Documents

May 17, 20001. 2 USB 2.0 Hub Details John Garney Hub Working Group Chair Intel Corporation John Garney Hub Working Group Chair Intel Corporation