ChromeOS Compatible - Displays Specification v1.0
Stay organized with collections
Save and categorize content based on your preferences.
Version: 1.0.1
Last updated: 2024-02-01
Legend
| Product Verb |
Development Action |
| "MUST" |
Mandatory product requirement |
| "SHOULD" |
Optional recommendation |
| "MAY" |
Nice to have |
Requirements Scope
This document defines the requirements that ChromeOS Compatible displays meet.
This specification should not be used for WWCB products, or a product designed
and certified together with a Chromebook.
Display Types
This document covers external displays that connect via HDMI, DisplayPort, or
USB Type-C. This specification does not cover displays with embedded USB ports
or embedded MST hubs.
Hardware and Visual Design
Visual Design
- Ports SHOULD be labeled consistently with the applicable
industry-standard logos
- Logos SHOULD comply with standards-appropriate marketing guidelines for
logo usage
- DisplayLink/Silicon Motion requirements/capabilities clearly
silkscreened on unit
- Thunderbolt requirements/capabilities clearly silkscreened on unit
Connectivity
- The display SHOULD include at least one video cable in the box
- The display MAY include any additional number of additional cables in
the box
- Included cable(s) MUST match the version of the connectivity standard
supported by the display
- For example, if the display supports HDMI 2.1, the included cable MUST
be an HDMI 2.1 cable
- All cables and adapters included in the box MUST meet ChromeOS
Compatible Cable requirements and ChromeOS Compatible Power Adapters
requirements[^1] specifications, but need not be officially WWCB
certified.
Product Requirements
USB-C
- If the display supportive native USB-C, it MUST pass the associated
requirements in the ChromeOS Compatible Dock spec
- The display MUST meet DP Alt-Mode requirements
- If the display supports Power Source role, it MUST pass "Power"
requirements
- If daisy chaining or video out from the display is supported, "HDMI out"
and/or "DisplayPort out" requirements MUST be met as well as MST
requirements
- If the display has native USB-A ports, the "USB-A" and "USB and PD
Behaviors" requirements MUST be met
Protocols and Compliance
- The display MUST default to the highest version of any connection
protocol it supports.
- For example, if the display supports DP1.2, it cannot default to DP1.1
- All inputs of the display SHOULD support the full resolution and refresh
rate advertised in Extended Display Identification Data (EDID) specification
available to download for the VESA members at their site [VESA Standards]
- For example, some "4k60" displays only offer 4k60 over DP, and limit
HDMI to 4k30 due to HDMI 1.4
- In the above case, if the display supports 4K60, it SHOULD have support
for DP 1.2 on DP port and HDMI 2.0 on HDMI port
- Similarly, if the DP input supports 4k60, the USB-C input SHOULD also
support 4k60 (in appropriate Pin Configuration given signaling
constraints)
- If the display implements HDMI, then the display MUST implement HDMI
Forum spec and pass HDMI Forum Compliance Test Suite for the HDMI version
implemented.
- If the display implements DisplayPort (DP), then the display MUST
implement VESA spec and pass VESA Link Layer and PHY conformance for the DP
version implemented. The VESA CTS specifications are available to the VESA
members for download at VESA Standards:
https://groups.vesa.org/wg/AllMem/home/get-vesa-standards
HPD
- Toggling of HDP signals for status change notification MUST follow section
5.2.4 of the VESA DP 2. Specification available to VESA members for download
at [VESA Standards]
- Timing between HPD and DPCD/DDC MUST meet HDMI and DisplayPort standards
- Both HDMI 1.4b Section 8.5 and DisplayPort 2.0 Section 2.12 specify
immediate availability upon HPD signal assertion.
- These specs are available to VESA members for download at [VESA
Standards]
- Passive HPD MUST be supported
- HPD MUST be asserted on all the inputs whenever the display is
connected to any input
DPRX
- If the display supports DisplayPort
- The display MUST support down spread (De-spreading of the
Regenerated Stream Clock)
- Display MUST indicate it is capable of supporting down-spread
link frequency in the DPCD by setting
MAX_DOWNSPREAD bit.
- The OUI MUST be properly set
- For example, the OUI MAY not be all zeros
Power
- When the display is put to sleep by the connected Chromebook, then it MUST
wake when the connected Chromebook sends the wake signal.. This means the
display MUST NOT have "deep sleep" states which are automatically
entered and require the user to push a button on the display to wake it up.
- On DisplayPort, the Chromebook will enter/exit sleep via the
SET_POWER_STATE bit in DPCD register 00600h SET_POWER
- On HDMI, the Chromebook will enter/exit sleep via valid video signal on
the wire
Identification
- The display's EDID MUST be valid and parse without errors
- Display EDID MUST meet the CTA-861-G spec
- For DP connections, EDID MUST pass VESA EDID Compliance Test
Specification v1.2
- EDID MUST report exactly one set of Manufacturer and Model information
- EDID MAY include display Name descriptor block containing the proper
model name
- EDID MUST include a valid, non-zero value in the serial number field of
Block 0 or the Serial Number extended block
- Each Manufacturer/Model pair MUST be unique to a given model
- Each Manufacturer/Model/Serial tuple MUST be universally unique
- The RGBW color coordinates in EDID MUST agree with the display color
spec typical value
- The display MUST output sRGB if it advertises sRGB in the EDID Feature
Support Detail byte (18h)
- The display MUST advertise one and only one mode marked as preferred per
EDID decode level
- The preferred mode SHOULD be the native resolution of the panel
- All preferred modes SHOULD match the native aspect ratio of the panel
- The EDID MUST report the accurate physical dimensions for the display
panel not including bezel in centimeters
HDCP
- The display MUST support HDCP 1.4
- The display SHOULD support HDCP 2.2
- The display MAY support HDCP 2.3 or later
- If the display is a 4K display or greater, the display MUST support HDCP
2.2
- The display MUST support the same HDCP version(s) on all inputs
- The display SHOULD have no discernable flicker (0 frames) when HDCP is
enabled or disabled
HDR
- If the display supports HDR, the display MUST meet the VESA DisplayHDR
specification for the HDR level claimed by the display
- If the display supports HDR, the display MUST have infoframe support
- If the display supports HDR, the display SHOULD support a 10 bit color
space
- If the display supports HDR, the display MAY support a 12 bit color
space
Audio
- If the display supports both built-in speaker and 3.5mm headphone output, it
SHOULD support switching between them via either user-directed or
automatic methods
- If the display supports audio input, the display MUST have infoframe
support
- If the display supports audio input, the display SHOULD at least support
2ch, 16-bit, 48K sampling rate audio format, and report the format in EDID
VRR
- If the display supports VRR/ VESA Adaptive Sync, the display MUST
advertise VRR display range (min and max refresh rates) in the EDID display
range descriptor block
- If the display supports VRR/ VESA Adaptive Sync, as per the VESA
specification the display MUST set
MSA_TIMING_PAR_IGNORED bit in the
DOWN_STREAM_PORT_COUNT register (DPCD Address 00007h, bit 6).
Revision History
| Date |
Version |
Notes |
| 2024-02-01 |
1.0.1 |
Republication on a new platform |
| 2023-10-18 |
1.0 |
Initial Partner Site Publication |
Except as otherwise noted, the content of this page is licensed under the Creative Commons Attribution 4.0 License, and code samples are licensed under the Apache 2.0 License. For details, see the Google Developers Site Policies. Java is a registered trademark of Oracle and/or its affiliates.
Last updated 2024-12-18 UTC.
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Missing the information I need","missingTheInformationINeed","thumb-down"],["Too complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2024-12-18 UTC."],[[["\u003cp\u003eThis specification defines requirements for external ChromeOS Compatible displays connected via HDMI, DisplayPort, or USB Type-C, excluding those with embedded USB ports or MST hubs.\u003c/p\u003e\n"],["\u003cp\u003eDisplays must adhere to industry standards for protocols like HDMI and DisplayPort, including HDCP for content protection and accurate EDID information for identification and compatibility.\u003c/p\u003e\n"],["\u003cp\u003eUSB-C displays need to comply with the ChromeOS Compatible Dock specification, especially concerning DP Alt-Mode, power delivery, and USB-A port functionality if present.\u003c/p\u003e\n"],["\u003cp\u003eDisplays should prioritize the highest supported connection protocol version, offer consistent resolution and refresh rates across all inputs, and manage power states effectively to ensure seamless Chromebook interaction.\u003c/p\u003e\n"],["\u003cp\u003eFor features like HDR and VRR, displays must meet the relevant VESA specifications and provide accurate information within their EDID to ensure proper functionality and compatibility with ChromeOS.\u003c/p\u003e\n"]]],[],null,["# ChromeOS Compatible - Displays Specification v1.0\n\nVersion: 1.0.1 \n\nLast updated: 2024-02-01\n\nLegend\n------\n\n| Product Verb | Development Action |\n|--------------|-------------------------------|\n| \"MUST\" | Mandatory product requirement |\n| \"SHOULD\" | Optional recommendation |\n| \"MAY\" | Nice to have |\n\nRequirements Scope\n------------------\n\nThis document defines the requirements that ChromeOS Compatible displays meet.\nThis specification should not be used for WWCB products, or a product designed\nand certified together with a Chromebook.\n\n### Display Types\n\nThis document covers external displays that connect via HDMI, DisplayPort, or\nUSB Type-C. This specification does not cover displays with embedded USB ports\nor embedded MST hubs.\n\nHardware and Visual Design\n--------------------------\n\n### Visual Design\n\n- Ports **SHOULD** be labeled consistently with the applicable industry-standard logos\n- Logos **SHOULD** comply with standards-appropriate marketing guidelines for logo usage\n - DisplayLink/Silicon Motion requirements/capabilities clearly silkscreened on unit\n - Thunderbolt requirements/capabilities clearly silkscreened on unit\n\n### Connectivity\n\n- The display **SHOULD** include at least one video cable in the box\n- The display **MAY** include any additional number of additional cables in the box\n- Included cable(s) **MUST** match the version of the connectivity standard supported by the display\n - For example, if the display supports HDMI 2.1, the included cable MUST be an HDMI 2.1 cable\n- All cables and adapters included in the box **MUST** meet [**ChromeOS\n Compatible Cable requirements**](/chromeos/peripherals/cc-passive-cables-v1) and **ChromeOS Compatible Power Adapters\n requirements**\\[\\^1\\] specifications, but need not be officially WWCB certified.\n\nProduct Requirements\n--------------------\n\n### USB-C\n\n- If the display supportive native USB-C, it **MUST** pass the associated requirements in the ChromeOS Compatible Dock spec\n - The display **MUST** meet DP Alt-Mode requirements\n - If the display supports Power Source role, it **MUST** pass \"Power\" requirements\n - If daisy chaining or video out from the display is supported, \"HDMI out\" and/or \"DisplayPort out\" requirements **MUST** be met as well as MST requirements\n - If the display has native USB-A ports, the \"USB-A\" and \"USB and PD Behaviors\" requirements **MUST** be met\n\n### Protocols and Compliance\n\n- The display **MUST** default to the highest version of any connection protocol it supports.\n - For example, if the display supports DP1.2, it cannot default to DP1.1\n- All inputs of the display **SHOULD** support the full resolution and refresh rate advertised in Extended Display Identification Data (EDID) specification available to download for the VESA members at their site \\[VESA Standards\\]\n - For example, some \"4k60\" displays only offer 4k60 over DP, and limit HDMI to 4k30 due to HDMI 1.4\n - In the above case, if the display supports 4K60, it SHOULD have support for DP 1.2 on DP port and HDMI 2.0 on HDMI port\n - Similarly, if the DP input supports 4k60, the USB-C input SHOULD also support 4k60 (in appropriate Pin Configuration given signaling constraints)\n- If the display implements HDMI, then the display **MUST** implement HDMI Forum spec and pass HDMI Forum Compliance Test Suite for the HDMI version implemented.\n- If the display implements DisplayPort (DP), then the display **MUST** implement VESA spec and pass VESA Link Layer and PHY conformance for the DP version implemented. The VESA CTS specifications are available to the VESA members for download at [VESA Standards](https://groups.vesa.org/wg/AllMem/home/get-vesa-standards): https://groups.vesa.org/wg/AllMem/home/get-vesa-standards\n\n### HPD\n\n- Toggling of HDP signals for status change notification MUST follow section 5.2.4 of the VESA DP 2. Specification available to VESA members for download at \\[VESA Standards\\]\n- Timing between HPD and DPCD/DDC MUST meet HDMI and DisplayPort standards\n - Both HDMI 1.4b Section 8.5 and DisplayPort 2.0 Section 2.12 specify immediate availability upon HPD signal assertion.\n - These specs are available to VESA members for download at \\[VESA Standards\\]\n- Passive HPD **MUST** be supported\n - HPD **MUST** be asserted on all the inputs whenever the display is connected to any input\n\n### DPRX\n\n- If the display supports DisplayPort\n - The display **MUST** support down spread (De-spreading of the Regenerated Stream Clock)\n - Display **MUST** indicate it is capable of supporting down-spread link frequency in the DPCD by setting `MAX_DOWNSPREAD` bit.\n - The OUI MUST be properly set\n - For example, the OUI MAY not be all zeros\n\n### Power\n\n- When the display is put to sleep by the connected Chromebook, then it MUST wake when the connected Chromebook sends the wake signal.. This means the display **MUST NOT** have \"deep sleep\" states which are automatically entered and require the user to push a button on the display to wake it up.\n - On DisplayPort, the Chromebook will enter/exit sleep via the `SET_POWER_STATE` bit in `DPCD register 00600h SET_POWER`\n - On HDMI, the Chromebook will enter/exit sleep via valid video signal on the wire\n\n### Identification\n\n- The display's EDID **MUST** be valid and parse without errors\n- Display EDID **MUST** meet the CTA-861-G spec\n- For DP connections, EDID **MUST** pass VESA EDID Compliance Test Specification v1.2\n- EDID **MUST** report exactly one set of Manufacturer and Model information\n- EDID **MAY** include display Name descriptor block containing the proper model name\n- EDID **MUST** include a valid, non-zero value in the serial number field of Block 0 or the Serial Number extended block\n- Each Manufacturer/Model pair **MUST** be unique to a given model\n- Each Manufacturer/Model/Serial tuple **MUST** be universally unique\n- The RGBW color coordinates in EDID **MUST** agree with the display color spec typical value\n- The display **MUST** output sRGB if it advertises sRGB in the EDID Feature Support Detail byte (18h)\n- The display **MUST** advertise one and only one mode marked as preferred per EDID decode level\n- The preferred mode **SHOULD** be the native resolution of the panel\n- All preferred modes **SHOULD** match the native aspect ratio of the panel\n- The EDID **MUST** report the accurate physical dimensions for the display panel not including bezel in centimeters\n\n### HDCP\n\n- The display **MUST** support HDCP 1.4\n- The display **SHOULD** support HDCP 2.2\n- The display **MAY** support HDCP 2.3 or later\n- If the display is a 4K display or greater, the display **MUST** support HDCP 2.2\n- The display **MUST** support the same HDCP version(s) on all inputs\n- The display **SHOULD** have no discernable flicker (0 frames) when HDCP is enabled or disabled\n\n### HDR\n\n- If the display supports HDR, the display **MUST** meet the VESA DisplayHDR specification for the HDR level claimed by the display\n- If the display supports HDR, the display **MUST** have infoframe support\n- If the display supports HDR, the display **SHOULD** support a 10 bit color space\n- If the display supports HDR, the display **MAY** support a 12 bit color space\n\n### Audio\n\n- If the display supports both built-in speaker and 3.5mm headphone output, it **SHOULD** support switching between them via either user-directed or automatic methods\n- If the display supports audio input, the display **MUST** have infoframe support\n- If the display supports audio input, the display **SHOULD** at least support 2ch, 16-bit, 48K sampling rate audio format, and report the format in EDID\n\n### VRR\n\n- If the display supports VRR/ VESA Adaptive Sync, the display **MUST** advertise VRR display range (min and max refresh rates) in the EDID display range descriptor block\n- If the display supports VRR/ VESA Adaptive Sync, as per the VESA specification the display **MUST** set `MSA_TIMING_PAR_IGNORED` bit in the `DOWN_STREAM_PORT_COUNT` register (DPCD Address 00007h, bit 6).\n\nRevision History\n----------------\n\n| Date | Version | Notes |\n|------------|---------|----------------------------------|\n| 2024-02-01 | 1.0.1 | Republication on a new platform |\n| 2023-10-18 | 1.0 | Initial Partner Site Publication |"]]
