On Mon, 30 Aug 2021, Jani Nikula <jani.nikula@xxxxxxxxx> wrote:
> The VESA Organization Vendor-Specific Data Block, defined in VESA
> DisplayID Standard v2.0, specifies the eDP Multi-SST Operation (MSO)
> stream count and segment pixel overlap.
>
> DisplayID v1.3 has Appendix B: DisplayID as an EDID Extension,
> describing how DisplayID sections may be embedded in EDID extension
> blocks. DisplayID v2.0 does not have such a section, perhaps implying
> that DisplayID v2.0 data should not be included in EDID extensions, but
> rather in a "pure" DisplayID structure at its own DDC address pair
> A4h/A5h, as described in VESA E-DDC Standard v1.3 chapter 3.
>
> However, in practice, displays out in the field have embedded DisplayID
> v2.0 data blocks in EDID extensions, including, in particular, some eDP
> MSO displays, where a pure DisplayID structure is not available at all.
>
> Parse the MSO data from the DisplayID data block. Do it as part of
> drm_add_display_info(), extending it to parse also DisplayID data to
> avoid requiring extra calls to update the information.
For reference, this is the EDID from a Lenovo ThinkPad X1 with eDP MSO
display. AFAICT, the display does not respond on A4h/A5h at all, it only
has the usual EDID at the usual DDC address.
BR,
Jani.
edid-decode (hex):
00 ff ff ff ff ff ff 00 06 af 13 10 00 00 00 00
00 1c 01 04 a5 1c 13 78 02 ee 95 a3 54 4c 99 26
0f 50 54 00 00 00 01 01 01 01 01 01 01 01 01 01
01 01 01 01 01 01 d5 2b 68 50 40 e0 2c 50 18 10
3a 00 1c bd 10 00 00 18 00 00 00 0f 00 00 00 00
00 00 00 00 00 00 00 00 00 20 00 00 00 fe 00 41
55 4f 0a 20 20 20 20 20 20 20 20 20 00 00 00 fe
00 42 31 33 35 51 41 4e 30 31 2e 30 20 0a 01 e1
70 20 08 06 00 7e 00 05 3a 02 92 00 20 61 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 90
----------------
Block 0, Base EDID:
EDID Structure Version & Revision: 1.4
Vendor & Product Identification:
Manufacturer: AUO
Model: 4115
Made in: 2018
Basic Display Parameters & Features:
Digital display
Bits per primary color channel: 8
DisplayPort interface
Maximum image size: 28 cm x 19 cm
Gamma: 2.20
Supported color formats: RGB 4:4:4
First detailed timing includes the native pixel format and preferred refresh rate
Color Characteristics:
Red : 0.6396, 0.3300
Green: 0.2998, 0.5996
Blue : 0.1503, 0.0595
White: 0.3134, 0.3291
Established Timings I & II: none
Standard Timings: none
Detailed Timing Descriptors:
DTD 1: 1128x1504 60.006 Hz 3:4 92.889 kHz 112.210 MHz (284 mm x 189 mm)
Hfront 24 Hsync 16 Hback 40 Hpol N
Vfront 3 Vsync 10 Vback 31 Vpol N
Manufacturer-Specified Display Descriptor (0x0f): 00 0f 00 00 00 00 00 00 00 00 00 00 00 00 00 20 '............... '
Alphanumeric Data String: 'AUO'
Alphanumeric Data String: 'B135QAN01.0 '
Extension blocks: 1
Checksum: 0xe1
----------------
Block 1, DisplayID Extension Block:
Version: 2.0
Extension Count: 0
Display Product Primary Use Case: Presentation display
Vendor-Specific Data Block (VESA):
Data Structure Type: eDP
Default Colorspace and EOTF Handling: sRGB
Number of Pixels in Hor Pix Cnt Overlapping an Adjacent Panel: 0
Multi-SST Operation: Two Streams (number of links shall be 2 or 4)
Checksum: 0x61
Checksum: 0x90
--
Jani Nikula, Intel Open Source Graphics Center
