Make the User Happy: Interoperability Do's and Don'ts

Transcription

1 Make the User Happy: Interoperability Do's and Don'ts Benson Leung Software Engineer, Chrome OS, Google Inc Taipei, Taiwan October 24 25,

2 Session Agenda Don't Start With Legacy Turn Off Unused Features Truth In Advertising Interop Uncommon Combos. Key Takeaways Q&A 2

3 Real World Bugs Names withheld to protect the innocent... (However, several real bugs from Google's own Type-C devices and accessories) 3

4 #1 Don't Start With Legacy 4

5 Unwise Idea: Adapting a Legacy USB design Early Type-C designs descended from existing A and µb stuff Sources - adapted directly from Type-A chargers Cables - adapted directly from Type-A to Micro-B cables Sinks (phones, tablets, others) - adapted from Micro-B sinks, inheriting hardware and generations worth of complex charging logic in firmware and software 5

6 Legacy adaptation in Power Sources Type-C Type-A 6

7 Type-C Spec Fig 4-7 Source Functional Model FET enables/disables VBUS, initially off (Vbus Cold) Separate Rp on CC1 & CC2 Source monitors CC1 & CC2 V for connection Source monitors CC1 & CC2 V for detach. Cold upon detach NOTE: C Receptacle, hence both CCs 7

8 Actual power supply in market # 1 No FET. VBUS is 5V always (VBUS hot) Nothing monitors CC1 & CC2 V for sink presence Nothing Monitors CC1 & CC2 V for sink detach Two Rps DON'T DO THIS. NOTE: C Receptacle, hence both CCs 8

9 Actual power supply in market # 1 How did this happen? Existing Type-A chargers always 5V on, VBUS Hot. Designer swapped existing A receptacle with C Bare minimum to get a (noncompliant) C charger to market - Or is it? DON'T DO THIS. NOTE: C Receptacle, hence both CCs 9

10 Power supply in market # 2 - Even Barer Same as #1, but second Rp is omitted CC1 & CC2 tied together (maybe) DON'T DO THIS. NOTE: C Receptacle, hence both CCs 10

11 Legacy adaptation In Type-C cables 11

12 Type-C to Type-A Legacy Cable Interop No charging or data when used w/ some devices (Google Chromebook Pixel and Pixel C) SS data in one orientation, HS data only in other 12

13 Legacy Host Adapter, Per Type-C Spec Fig kω ± 5% Must be "Default USB Power" 13

14 Legacy Host Adapter, Bad Cable DON'T DO THIS. NONE??? Consequence : Compliant devices depend on vrd for orientation, power, and presence. Many don't charge, or don't mux SSTX SSRX with missing Rp. 14

15 "USB 3.0 C to C cable" Interop USB 3.1 data to SSD and phone work USB 2.0 works Charging seems to work DP Alt mode to monitor fails 15

16 "USB 3.0 C to C Cable" ACT result TX2 and RX2 pairs missing Ra missing SBU1/SBU2 missing emarker missing Advanced Cable Tester courtesy of Total Phase 16

17 What they did, and why. Started with USB 3.0 A-to-B Replaced As and Bs with C plugs Added a CC wire Tested, worked for them for data Never tested Alt Modes DON'T DO THIS. 17

18 Legacy adaptation in Power Sinks 18

19 Phone Symptoms of Legacy Design 1. No charging from Vbus Cold adapters 2. Slow charging from compliant 1.5A & 3A sources 3. Overdraw some power sources (PCs). 19

20 Phone user might encounter... No Charging Type-C and PD charger, 60W 20

21 Google 60W "Zinger" - Captive Cable, PD USB PD - 5V 3A, 12V 3A, 20V 3A (predates Section 10 Power Rules, complies with Power Profiles in PD 2.0) Type-C - Rp-3A0 VBUS Cold, as required for all PD power sources No BC 1.2 DCP - Dp Dn floating 21

22 Google 60W "Zinger" - Captive Cable, PD USB PD - 5V 3A, 12V 3A, 20V 3A (predates Section 10 Power Rules, complies with Power Profiles in PD 2.0) Type-C - Rp-3A0 VBUS Cold, as required for all PD power sources No BC 1.2 DCP - Dp Dn floating 22

23 Type-C Spec Fig 4-9 Sink Functional Model Separate Rds on CC1 & CC2 Rds required to trigger VBUS Cold Type-C sources Sink monitors VBUS for connection Sink determines Current advertisement by reading vrd NOTE: C Receptacle, hence both CCs 23

24 Legacy HW - Actual Sink #1 - No charging Sink monitors VBUS for connection No Rds Vbus Hot required, won't trigger Vbus Cold sinks Ignores Rp on source side for current limit. Someone thought Type-C was Micro-B in a different shape and swapped it. NOTE: C Receptacle, hence both CCs DON'T DO THIS. 24

25 Legacy in Sink Firmware and Software 25

26 Phone user might encounter... Slow Charging Type-C and PD charger, 60W 26

27 Google 60W "Zinger" - Captive Cable, PD USB PD - 5V 3A, 12V 3A, 20V 3A (predates Section 10 Power Rules, complies with Power Profiles in PD 2.0) Type-C - Rp-3A0 VBUS Cold, as required for all PD power sources No BC 1.2 DCP - Dp Dn floating 27

28 Google 60W "Zinger" - Captive Cable, PD, No BC USB PD - 5V 3A, 12V 3A, 20V 3A (predates Section 10 Power Rules, complies with Power Profiles in PD 2.0) Type-C - Rp-3A0 VBUS Cold, as required for all PD power sources No BC 1.2 DCP - Dp Dn floating No legacy µb sink can attach to Zinger b/c passive CRecpt-to-µB adapters not allowed by spec Compliant Type-C and PD sinks will use Type-C 3A current or PD to get proper current limit 28

29 Legacy SW - Sink #2 only ~400mA from Zinger vrd on CC2 is 1.7V, which is within range for vrd-3.0 Phone ignores. Falls back to floating DpDn charger behavior 29

30 Table 4-17 Precedence of power source usage 30

31 Power Source Precedence as Pseudocode int curr_limit_ma; if (sink_supports_pd && source_is_pd) { curr_limit_ma = get_pd_curr_limit(); /* PD negotiation here */ goto END; } type_c_curr = get_advertisment_from_cc_vrd(); switch (type_c_curr) { case TYPE_C_3A0: curr_limit_ma = 3000; break; case TYPE_C_1A5: curr_limit_ma = 1500; break; case TYPE_C_DEFAULT: if (is_bc12_cdp) curr_limit_ma = 1500; else if (is_bc12_dcp) curr_limit_ma = min(1500, get_bc12_dcp_cur_limit()); /* Legacy ICL discovery here */ else /* sdp */ curr_limit_ma = DEFAULT_USB; break; } 31

32 Sink #2 Pseudocode - Ignores Type-C current int curr_limit_ma; if (sink_supports_pd && source_is_pd) { curr_limit_ma = get_pd_curr_limit(); /* PD negotiation here */ goto END; } DON'T DO THIS. type_c_curr = get_advertisment_from_cc_vrd(); switch (type_c_curr) { case TYPE_C_3A0: curr_limit_ma = 3000; break; case TYPE_C_1A5: curr_limit_ma = 1500; break; case TYPE_C_DEFAULT: if (is_bc12_cdp) curr_limit_ma = 1500; else if (is_bc12_dcp) curr_limit_ma = min(1500, get_bc12_dcp_cur_limit()); /* Legacy ICL discovery here */ else /* sdp */ curr_limit_ma = DEFAULT_USB; break; } 32

33 Some Sinks intentionally snub vrd-3.0a Several phone manufacturers detect vrd-3.0a, but ignore it intentionally in their charging logic. Reason: Rp-3.0A was abused by out of spec A-to-C cables with 10kΩ resistors which are still in the ecosystem, so 3A level can never be trusted. Billed as a "safety feature" Decision punishes compliant Type-C 3A power sources with slower than intended charging. HIGHLY Counterproductive. Don't Do This. This is a workaround to an ecosystem problem that only hurts compliant chargers, and rewards noncompliant cables. When you see vrd-3a, use 3A as a current limit. 33

34 Phone user might encounter... Overcurrent Scenario: User plugs Type-C device into new Type-C computer (MacBook Pro, Chromebook, Windows PCs, etc) to sync data or charge Scary OS warning about using too much power. Device disconnects. 34

35 Dual Port 22.5W - "Donnette" w/ Sub-States! Port A - Rp-3A0 Initially Port B - Rp-1A5 Initially Each port may supply 3.0A Supports just Type-C, no PD Load balances between Ports A and B, flipping Rp-3A0 and Rp-1A5 between ports depending on load on Port B. Relies on Sink Power Sub-States: Sinks on both ports may observe dynamic vrd 35

36 Donnette Sub-State Load Balancing In Action Port A, with Chromebook Sink Port B, with adjustable DC load 36

37 Donnette Sub-State Load Balancing In Action Port A, with Chromebook Sink Port B, with adjustable DC load 37

38 Donnette Sub-State Load Balancing In Action Port A, with Chromebook Sink, Proper Sub-State Current Limit Following 38

39 Legacy SW - Sink #3 - Sub-States Sink not respecting Sink Power Sub-States. Overdrawing during periods of vrd-1.5 by drawing 1.9A DON'T DO THIS. Donnette Port A, Noncompliant Sink Possible explanations: 1. Sink software ignores Type-C Current Detection entirely (like example Sink #2). a. Falls back to DCP, which Donnettes presents b. Overdraws BC 1.2's 1.5A limit too Sink detects Type-C Current Detection, but only at initial connection time. a. Inherited behavior from BC 1.2 logic on Micro-B/Type-A, where source can't change power capability during same connected session. b. IRQ from Type-C controller not wired up. CC advertisement only polled at connect time. 39

40 Many USB-C PCs already rely on Sub-States Samsung Chromebook Plus Apple MacBook Pro 40

41 Sink Power Sub-States Required by Android CDD USB peripheral mode [C-1-3] MUST detect 1.5A and 3.0A chargers per the Type-C resistor standard and MUST detect changes in the advertisement if they support Type-C USB. Android team will test all new Type-C phone designs. Test and fix your phones before launch, or you'll get flagged for a CDD violation. 41

42 Legacy Source/Cable/Sink Key Takeaways Start from scratch with Type-C, then add legacy support. Type-C spec has clear and simple guidance on adding legacy support (BC 1.2, etc). No such guidance for adapting legacy designs for C. Taking a Type-A or Micro-B design and "fixing it up" to be Type-C is far harder and trickier, especially if designer doesn't understand all of the implications. 42

43 #2 Turn off unused features! 43

44 Be wary of leaving on extra features Modern Type-C Controllers' varied capabilities Fixed UFP operation Fixed DFP operation Act as SOP' in an EMCA Built in Dead Battery Rd for UFPs Dual Role Toggling for DRPs Try.SRC/Try.SNK PD 44

45 Extra Features - Dedicated Power SRC #1 4.8A Total 3A 2.4A 45

46 Extra Features - Dedicated Power SRC #1 4.8A Total 3A Only Charges Laptop 50% of time. 2.4A 46

47 Extra Features - Dedicated Power SRC 4.8A Total 3A 2.4A DON'T DO THIS. Dual Role Toggling on a fixed source-only AC adapter 47

48 Extra Features - Dedicated Power SRC DRP Try.SRC 4.8A Total 3A DRP Try.SRC 2.4A DON'T DO THIS. Would you kindly not enable DRP when building a fixed source? 48

49 Extra Features - Dedicated Power SRC #2 Car ON 5V3A 9V3A 49

50 Extra Features - Dedicated Power SRC #2 DON'T DO THIS. Car OFF DEAD BATT Rds 5V3A 9V3A Would you kindly not enable Dead Batt Rd when building a fixed source? High-Z CCs, please! 50

51 Speaking of Rds... Here's an advanced cable 15V 5V3A 9V3A 15V3A 15V USB 3.1 Gen 2, 3A Full Featured Cable 45W, 15V safe Credit to Nathan K. for discovering this. 51

52 What's supposed to happen. vsafe0v 5V3A 9V3A 15V3A vsafe0v USB 3.1 Gen 2, 3A Full Featured Cable Credit to Nathan K. for discovering this. 52

53 What actually happened. 15V 5V3A 9V3A 15V3A 15V USB 3.1 Gen 2, 3A Full Featured Cable Credit to Nathan K. for discovering this. 53

54 What could have happened easily. 15V 5V3A 9V3A 15V3A 15V USB 3.1 Gen 2, 3A Full Featured Cable 5V only Credit to Nathan K. for discovering this. 54

55 EMCA Functional model 55

56 emarked Cable with Extra Rd Credit to Nathan K. for discovering this. DON'T DO THIS. 56

57 Truth in Advertising 57

58 Truth in Advertising Make sure all of the following match/are consistent 1. Information on web site or Amazon product listing 2. Information on packaging 3. Markings on product 4. Analog adv, if applicable (Rp) 5. Digital adv, if applicable (SRCCAP, SINKCAP, DISC_IDENT) 6. Actual capability 58

59 Ex #1: USB 3.1 Gen 1, 5A Full-Featured Cable 3A rating instead of 5A - slower charging when used with >60W source + sink Gen 2 speed instead of Gen 1 - Gen 2 host + client may fail data if cable SI not tuned for 10gbps DON'T DO THIS. Advanced Cable Tester courtesy of Total Phase 59

60 Fill out VID:PID and others accurately! Apple, Google, and others capture this information in logs Accurate information will help identify interoperability problems in the field from user bug reports. Applies to cables, power sources, power sinks, and USB devices. Don't skip or lie about VID:PID 60

61 Ex 2: 10W Car Adapter 5V2A, 9V1.67A 12V1.25A No PD Support Supports 5V2A, 9V1.67A, 12V1.25A using prohibited proprietary method (violates Section 4.8.2), according to marketing material and device's markings DON'T DO THIS. 61

62 Ex 2: 10W Car Adapter Rp-3.0A DON'T DO THIS. 5V2A, 9V1.67A 12V1.25A Rp-3.0A measured Overcurrent Protection set at 5V ~2.1A 62

63 Ex 2: 10W Car Adapter Rp-3.0A 5V2A, 9V1.67A 12V1.25A 0W - OCP 5V 3A capable sink Compliant 5V 3A Type-C Sink immediately OCPs Proper Rp to match device markings is Rp-1.5A 63

64 Ex 3: 30W Power Supply What Amazon / Web Site says: 30W Output 5V 3A, 9V 2A, 15V 2A, 20V 1.5A max What label says: What SRCCAP says: SRCCAP 5000mV/3000mA 9000mV/3000mA 15000mV/3000mA DON'T DO THIS. 45W 64

65 Ex 3: 30W Power Supply - Possibility 1 45W 30W (Digital 45W) 45W Chromebook Underlying supply can actually support 45W. Charging is stable. 65

66 Ex 3: 30W Power Supply - Possibility 2 0W - OCP 30W (Digital 45W) 45W Chromebook Charger OCP set to just over 2A at 15V. 45W laptop will try to draw 3A, and trip OCP. 66

67 Ex 3: 30W Power Supply - Possibility 3 ~45W at first 30W (Digital 45W) 45W Chromebook Underlying supply actually 30W supply. OCP set to above 3A at 15V. Charger gets hot... 67

68 Ex 3: 30W Power Supply - Possibility 3 #At first > tw vbus VBUS = mv ; ma # 5 minutes later > tw vbus VBUS = mv ; ma # 10 minutes later > tw vbus VBUS = 9340 mv ; ma Charger gets REALLY hot. 68

69 Ex 4: Phone as a Source! What Phone's SRCCAP says: SRCCAP 5000mV/900mA What Phone's Pre-PD Rp says: Rp-1.5A What Phone's OCP is: 1100mA DON'T DO THIS. Violates PD Power Rules Compliant non-pd Type-C Sinks may overcurrent the phone. 69

70 Ex 4: Phone as a Source! What Phone's SRCCAP says: SRCCAP 5000mV/900mA What Phone's Pre-PD Rp says: Rp-1.5A Rp-DefaultUSB What Phone's OCP is: 1100mA PD Rules OK. Same limit PD vs. No PD. Maximum sink will draw less than overcurrent. 70

71 Ex 5: Power Bank or Docking station "UP" bit USB-C wired docking station (or Portable Battery Pack) sets Dual-Role Power, but not Unconstrained Power. 71

72 Ex 5: Power Bank or Docking station "UP" bit 5V, but 0A Dock w/ No "UP" When attached to Chromebook, DRP +!UP results in 5V negotiated, but 0 A, no charging. 72

73 Ex 5: Power Bank or Docking station "UP" bit 5V, but 0A Chromebooks use DRP +!UP to detect when attached to another Chromebook! Won't charge from each other by default (unless user orders). 73

74 Ex 5: Power Bank or Docking station "UP" bit 45W Dock w/ "UP" When building a DRP Docking Station or a Portable Battery Pack, please set UP. 74

75 Test Wide! Interop Uncommon Combos! 75

76 Test with emarked Cables! Kinds of C-to-C cables: 1. USB 2.0 3A 2. USB 2.0 5A 3. USB 3.1 Gen 1 3A 4. USB 3.1 Gen 1 5A emarker Required 5. USB 3.1 Gen 2 3A 6. USB 3.1 Gen 2 5A Significant difference between emarked and non-emarked: Ra on Vconn 76

77 Recall Shorted CC1 + CC2 Power Source DON'T DO THIS. NOTE: C Receptacle, hence both CCs 77

78 Shorted CC Source + EMCA 78

79 Shorted CC Source + EMCA 1. If Vbus Hot, 3A Power source mistaken for Default USB, charging slowly 2. If Vbus Cold, 0.4V lower than 3A activation min (.85V) No Charging 79

80 Shorted CC1 Source + EMCA + DRP w/ Audio Shorted CC Source EMCA DRP, presenting as Source DRP may see Ra-Ra, and drop into Audio Adapter Accessory Mode! 80

81 Combo - PD 3.0 PPS Supply and PD 2.0 Sink Brand new USB PD 3.0 PPS Supply with existing PD 2.0 Sink: SRC/0 [71a1]SRCCAP 5000mV/3000mA 9000mV/3000mA 12000mV/3000mA 15000mV/3000mA 20000mV/2250mA 39000mV/5720mA 13400mV/5530mA SNK/0 [0041]GOODCRC SRC/1 [0363]ACCEPT SNK/1 [0241]GOODCRC SRC/2 [0566]PSRDY SNK/2 [0441]GOODCRC SNK/1 [1242]REQUEST{7} 7004b12c SRC/1 [0361]GOODCRC SRC/3 [0764]REJECT SNK/3 [0641]GOODCRC Result: Slow charging, 5V only PD 2.0 Sink 81

82 Combo - PD 3.0 PPS Supply and PD 2.0 Sink New USB PD 3.0 PPS Supply with existing PD 2.0 Sink: SRC/0 [71a1]SRCCAP 5000mV/3000mA 9000mV/3000mA 12000mV/3000mA 15000mV/3000mA 20000mV/2250mA 39000mV/5720mA 13400mV/5530mA SNK/0 [0041]GOODCRC Augmented PDOs; PD 2.0 Analyzer (and sink) misdecode SRC/1 [0363]ACCEPT SNK/1 [0241]GOODCRC Sink mistakenly requests APDO using PD 2.0 REQUEST SRC/2 [0566]PSRDY SNK/2 [0441]GOODCRC SNK/1 [1242]REQUEST{7} 7004b12c SRC/1 [0361]GOODCRC SRC/3 [0764]REJECT SNK/3 [0641]GOODCRC Result: Slow charging, 5V only PD 2.0 Sink 82

83 PD 3.0 PPS + PD 2.0 PSA! Check that PD 2.0 sinks disregard all PDOs with Reserved value 11b. Firmware update may be required! PD 3.0 PDO PD 2.0 PDO 83

84 Combo - Pixel phone, Apple hub, 3p charger Third Party Type-C/PD Charger Interop Result: Slow charging at phone. 5V 500mA only. Expected ~9V fast charging. 84

85 PD Trace Between Apple hub, 3p charger SRC/0 SNK/0 SNK/0 SRC/0 SRC/1 SNK/1 SRC/2 SNK/2 SRC/3 SNK/3 SNK/1 SRC/1 SRC/4 SNK/4 SNK/2 SRC/2 SRC/5 SNK/5 SRC/6 SNK/6 [51a1]SRCCAP 5000mV/3000mA 9000mV/3000mA 12000mV/3000mA 15000mV/3000mA 20000mV/3000mA [0041]GOODCRC [1042]REQUEST{1} [0161]GOODCRC [0363]ACCEPT [0241]GOODCRC [0566]PSRDY [0441]GOODCRC [176f]VDM Vff00:DISCID,INI:ff [0641]GOODCRC [424f]VDM Vff00:DISCID,ACK:ff ac [0361]GOODCRC [2961]SRCCAP 5000mV/3000mA 15000mV/2000mA [0841]GOODCRC [1442]REQUEST{1} [0561]GOODCRC [0b63]ACCEPT [0a41]GOODCRC [0d66]PSRDY [0c41]GOODCRC 85

86 PD Trace Between Apple hub, 3p charger SRC/0 SNK/0 SNK/0 SRC/0 SRC/1 SNK/1 SRC/2 SNK/2 SRC/3 SNK/3 SNK/1 SRC/1 SRC/4 SNK/4 SNK/2 SRC/2 SRC/5 SNK/5 SRC/6 SNK/6 [51a1]SRCCAP 5000mV/3000mA 9000mV/3000mA 12000mV/3000mA 15000mV/3000mA 20000mV/3000mA [0041]GOODCRC [1042]REQUEST{1} [0161]GOODCRC [0363]ACCEPT [0241]GOODCRC [0566]PSRDY [0441]GOODCRC [176f]VDM Vff00:DISCID,INI:ff [0641]GOODCRC [424f]VDM Vff00:DISCID,ACK:ff ac [0361]GOODCRC [2961]SRCCAP 5000mV/3000mA 15000mV/2000mA [0841]GOODCRC [1442]REQUEST{1} [0561]GOODCRC [0b63]ACCEPT [0a41]GOODCRC [0d66]PSRDY [0c41]GOODCRC 60W, PD Rules Compliant 30W, Missing Normative 9V 86

87 Third Party Vendor specific (Apple) hack SRC/0 SNK/0 SNK/0 SRC/0 SRC/1 SNK/1 SRC/2 SNK/2 SRC/3 SNK/3 SNK/1 SRC/1 SRC/4 SNK/4 SNK/2 SRC/2 SRC/5 SNK/5 SRC/6 SNK/6 [51a1]SRCCAP 5000mV/3000mA 9000mV/3000mA 12000mV/3000mA 15000mV/3000mA 20000mV/3000mA [0041]GOODCRC [1042]REQUEST{1} [0161]GOODCRC [0363]ACCEPT [0241]GOODCRC [0566]PSRDY [0441]GOODCRC [176f]VDM Vff00:DISCID,INI:ff [0641]GOODCRC [424f]VDM Vff00:DISCID,ACK:ff ac [0361]GOODCRC [2961]SRCCAP 5000mV/3000mA 15000mV/2000mA [0841]GOODCRC [1442]REQUEST{1} [0561]GOODCRC [0b63]ACCEPT [0a41]GOODCRC [0d66]PSRDY [0c41]GOODCRC "Who Are You?" "Apple hub VID:PID" "Apples Get Less" 87

88 What happened? 1. Apple releases ipad Pro in November 2015 (Tells no one about PD). 2. March 2016: Apple releases new C-to-Lightning cable, which lets ipad Pro 12.9" use USB PD and higher voltage. 3. Charger manufacturers discover a bug: ipad Pro 12.9" only selects 5V from some PD chargers 4. Manufacturers discover "fix" empirically: list only two PDOs. Craft a hidden workaround based on VID:PID 5. "Apple Flow" workaround goes into wide production, propagates to many chargers through common chipset firmware 6. Non-Apple Devices connected to these chargers via Apple dongles get reduced PDOs too. 88

89 What should have happened? 1. Apple releases ipad Pro in November 2015 (Tells no one about PD). 2. March 2016: Apple releases new C-to-Lightning cable, which lets ipad Pro 12.9" use USB PD and higher voltage. 3. Charger manufacturers discover a bug: ipad Pro 12.9" only selects 5V from some PD chargers 4. Manufacturers report a bug to Apple 5. Apple fixes bug, sends fw update to ipads 6. Everybody's happy. DON'T USE HIDDEN MODES OF OPERATION AS WORKAROUNDS 89

90 Key Takeaways 90

91 5 Key Takeaways 1. Keep your PD Analyzer handy, learn how to use it effectively 2. Test as many combinations as possible 6 kinds of C-to-C cable Vbus Hot vs Vbus Cold chargers Legacy cables and chargers Low wattage vs High wattage sinks Non-PD vs. PD Sources (of a variety of wattage) 3. Every piece of Type-C gear must stand on its own Swapping bundled gear for compliant cables, chargers, etc should have predictable results. Each individual piece of gear should be compliant "Only compatible with our own products and accessories" not acceptable 4. Know what to expect, file bugs when something defies your expectation 5. Test interop with your competitors' products too 91

92 Report bugs directly to Manufacturers When you find an issue in a product, file a bug with the manufacturer! Resist urge to bake vendor and product specific workarounds into your firmware. Apple Bug Report System: Chromebook Issue Tracker: Android/Pixel Phone Issue Tracker: Your Company's Bug Report System? Please provide a public link to report issues to make the ecosystem healthier! 92

93 Thank you! 93

94 Q&A Session 94

95 Backup Materials 95

96 Aside: Google's Power Adapter Line Adapter Max Power Type-C Rp Power Delivery PDOs BC 1.2 DCP 18W Rp-3.0A Yes 5V3A, 9V2A Yes 60W Rp-3.0A Yes 5V3A, 12V3A, 20V3A No 22.5W ( ) Rp-3.0A + Rp1.5A No N/A Yes "Tetra" "Zinger" "Donnette" 96

97 Design Considerations: Digital USB-C to 3.5mm 1. Must use a single Rd (no Ra-Ra for Analog) 2. Only present audio out/in when appropriate. Detached dongle should have no audio endpoint (or support UAC2/3 HPD) 3. Must HDP and transition quickly. 4. Implement Android 4-button Headset Spec as USB HID 5. Power consumption must be reasonable 2.5mA suspend 97

98 Legacy Host Adapter, Per Spec 56 kω ± 5% Must be "Default USB Power" 98

99 3A Noncompliant legacy host adapters 56kΩ 10kΩ!!! Consequence : 3A capable devices may overcurrent/damage older chargers/hubs/pcs. 99