Re: [PATCH 2/2] drm/display: hdmi: Mention Infoframes testing with edid-decode

From: Hans Verkuil
Date: Fri Mar 07 2025 - 08:11:53 EST

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In reply to: Maxime Ripard: "[PATCH 2/2] drm/display: hdmi: Mention Infoframes testing with edid-decode"
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Hi Maxime,

On 06/03/2025 18:17, Maxime Ripard wrote:
> edid-decode gained recently support to check that infoframes are
> compliant and match the EDID the monitor exposes.
>
> Since the HDMI helpers provide those infoframes in debugfs, it makes it
> easy to check from userspace that the drivers (and helpers) behave
> properly.
>
> Let's document it.
>
> Cc: Hans Verkuil <hverkuil@xxxxxxxxx>
> Signed-off-by: Maxime Ripard <mripard@xxxxxxxxxx>
> ---
> drivers/gpu/drm/display/drm_hdmi_state_helper.c | 240 ++++++++++++++++++++++++
> 1 file changed, 240 insertions(+)
>
> diff --git a/drivers/gpu/drm/display/drm_hdmi_state_helper.c b/drivers/gpu/drm/display/drm_hdmi_state_helper.c
> index 24bfc82bf9b02bf3201d97432e3c239ccc8714b4..86f812b89f0e51abc24910898c114d6b08a78edf 100644
> --- a/drivers/gpu/drm/display/drm_hdmi_state_helper.c
> +++ b/drivers/gpu/drm/display/drm_hdmi_state_helper.c
> @@ -16,10 +16,250 @@
> * in the form of KMS helpers.
> *
> * It contains TMDS character rate computation, automatic selection of
> * output formats, infoframes generation, etc.
> *
> + * Infoframes Compliance
> + * ~~~~~~~~~~~~~~~~~~~~~
> + *
> + * Drivers using the helpers will expose the various infoframes
> + * generated according to the HDMI specification in debugfs.
> + *
> + * Compliance can then be tested using a recent-enough ``edid-decode``
> + * version (released after summer 2024). A sample run would look like:
> + *
> + * .. code-block:: bash
> + *
> + * # edid-decode \
> + * -I /sys/kernel/debug/dri/1/HDMI-A-1/infoframes/audio \
> + * -I /sys/kernel/debug/dri/1/HDMI-A-1/infoframes/avi \
> + * -I /sys/kernel/debug/dri/1/HDMI-A-1/infoframes/hdmi \
> + * -I /sys/kernel/debug/dri/1/HDMI-A-1/infoframes/hdr_drm \
> + * -I /sys/kernel/debug/dri/1/HDMI-A-1/infoframes/spd \
> + * /sys/class/drm/card1-HDMI-A-1/edid \
> + * -c
> + *
> + * edid-decode (hex):
> + *
> + * 00 ff ff ff ff ff ff 00 1e 6d f4 5b 1e ef 06 00
> + * 07 20 01 03 80 2f 1a 78 ea 24 05 af 4f 42 ab 25
> + * 0f 50 54 21 08 00 d1 c0 61 40 01 01 01 01 01 01
> + * 01 01 01 01 01 01 56 5e 00 a0 a0 a0 29 50 30 20
> + * 35 00 d1 06 11 00 00 1a 00 00 00 fd 00 3b 3d 1e
> + * 70 1e 00 0a 20 20 20 20 20 20 00 00 00 fc 00 4c
> + * 47 20 53 44 51 48 44 0a 20 20 20 20 00 00 00 ff
> + * 00 32 30 37 4e 54 52 4c 44 43 34 33 30 0a 01 43
> + *
> + * 02 03 29 71 23 09 07 07 4b 01 03 04 90 12 13 1f
> + * 22 5d 5e 5f 83 01 00 00 6d 03 0c 00 10 00 b8 3c
> + * 20 00 60 01 02 03 e2 00 6a 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 ee
> + *
> + * ----------------
> + *
> + * Block 0, Base EDID:
> + * EDID Structure Version & Revision: 1.3
> + * Vendor & Product Identification:

This looks odd: the two lines above should be aligned, but they are not.

Some copy-and-paste issue perhaps?

> + * Manufacturer: GSM
> + * Model: 23540
> + * Serial Number: 454430 (0x0006ef1e)
> + * Made in: week 7 of 2022
> + * Basic Display Parameters & Features:
> + * Digital display
> + * Maximum image size: 47 cm x 26 cm
> + * Gamma: 2.20
> + * DPMS levels: Standby Suspend Off
> + * RGB color display
> + * First detailed timing is the preferred timing
> + * Color Characteristics:
> + * Red : 0.6835, 0.3105
> + * Green: 0.2587, 0.6679
> + * Blue : 0.1445, 0.0585
> + * White: 0.3134, 0.3291
> + * Established Timings I & II:
> + * DMT 0x04: 640x480 59.940476 Hz 4:3 31.469 kHz 25.175000 MHz
> + * DMT 0x09: 800x600 60.316541 Hz 4:3 37.879 kHz 40.000000 MHz
> + * DMT 0x10: 1024x768 60.003840 Hz 4:3 48.363 kHz 65.000000 MHz
> + * Standard Timings:
> + * DMT 0x52: 1920x1080 60.000000 Hz 16:9 67.500 kHz 148.500000 MHz
> + * DMT 0x10: 1024x768 60.003840 Hz 4:3 48.363 kHz 65.000000 MHz
> + * Detailed Timing Descriptors:
> + * DTD 1: 2560x1440 59.950550 Hz 16:9 88.787 kHz 241.500000 MHz (465 mm x 262 mm)
> + * Hfront 48 Hsync 32 Hback 80 Hpol P
> + * Vfront 3 Vsync 5 Vback 33 Vpol N
> + * Display Range Limits:
> + * Monitor ranges (GTF): 59-61 Hz V, 30-112 kHz H, max dotclock 300 MHz
> + * Display Product Name: 'LG SDQHD'
> + * Display Product Serial Number: '207NTRLDC430'
> + * Extension blocks: 1
> + * Checksum: 0x43
> + *
> + * ----------------
> + *
> + * Block 1, CTA-861 Extension Block:
> + * Revision: 3
> + * Basic audio support
> + * Supports YCbCr 4:4:4
> + * Supports YCbCr 4:2:2
> + * Native detailed modes: 1
> + * Audio Data Block:
> + * Linear PCM:
> + * Max channels: 2
> + * Supported sample rates (kHz): 48 44.1 32
> + * Supported sample sizes (bits): 24 20 16
> + * Video Data Block:
> + * VIC 1: 640x480 59.940476 Hz 4:3 31.469 kHz 25.175000 MHz
> + * VIC 3: 720x480 59.940060 Hz 16:9 31.469 kHz 27.000000 MHz
> + * VIC 4: 1280x720 60.000000 Hz 16:9 45.000 kHz 74.250000 MHz
> + * VIC 16: 1920x1080 60.000000 Hz 16:9 67.500 kHz 148.500000 MHz (native)
> + * VIC 18: 720x576 50.000000 Hz 16:9 31.250 kHz 27.000000 MHz
> + * VIC 19: 1280x720 50.000000 Hz 16:9 37.500 kHz 74.250000 MHz
> + * VIC 31: 1920x1080 50.000000 Hz 16:9 56.250 kHz 148.500000 MHz
> + * VIC 34: 1920x1080 30.000000 Hz 16:9 33.750 kHz 74.250000 MHz
> + * VIC 93: 3840x2160 24.000000 Hz 16:9 54.000 kHz 297.000000 MHz
> + * VIC 94: 3840x2160 25.000000 Hz 16:9 56.250 kHz 297.000000 MHz
> + * VIC 95: 3840x2160 30.000000 Hz 16:9 67.500 kHz 297.000000 MHz
> + * Speaker Allocation Data Block:
> + * FL/FR - Front Left/Right
> + * Vendor-Specific Data Block (HDMI), OUI 00-0C-03:
> + * Source physical address: 1.0.0.0
> + * Supports_AI
> + * DC_36bit
> + * DC_30bit
> + * DC_Y444
> + * Maximum TMDS clock: 300 MHz
> + * Extended HDMI video details:
> + * HDMI VICs:
> + * HDMI VIC 1: 3840x2160 30.000000 Hz 16:9 67.500 kHz 297.000000 MHz
> + * HDMI VIC 2: 3840x2160 25.000000 Hz 16:9 56.250 kHz 297.000000 MHz
> + * HDMI VIC 3: 3840x2160 24.000000 Hz 16:9 54.000 kHz 297.000000 MHz
> + * Video Capability Data Block:
> + * YCbCr quantization: No Data
> + * RGB quantization: Selectable (via AVI Q)
> + * PT scan behavior: Always Underscanned
> + * IT scan behavior: Always Underscanned
> + * CE scan behavior: Always Underscanned
> + * Checksum: 0xee Unused space in Extension Block: 86 bytes
> + *
> + * ----------------
> + *
> + * edid-decode SHA: 5332a3b76080 2024-11-19 07:53:00

I recommend that you get the latest edid-decode version from https://git.linuxtv.org/v4l-utils.git/
so that the documentation is at least corresponding to the most recent version.

Should there be a link to the official git repo as well?

> + *
> + * Warnings:
> + *
> + * Block 1, CTA-861 Extension Block:
> + * IT Video Formats are overscanned by default, but normally this should be underscanned.
> + * Video Data Block: VIC 1 and the first DTD are not identical. Is this intended?
> + * Video Data Block: All VICs are in ascending order, and the first (preferred) VIC <= 4, is that intended?
> + * Video Capability Data Block: Set Selectable YCbCr Quantization to avoid interop issues.
> + * Video Capability Data Block: S_PT is equal to S_IT and S_CE, so should be set to 0 instead.
> + * Display Product Serial Number is set, so the Serial Number in the Base EDID should be 0.
> + * Add a Colorimetry Data Block with the sRGB colorimetry bit set to avoid interop issues.
> + * EDID:
> + * Base EDID: Some timings are out of range of the Monitor Ranges:
> + * Vertical Freq: 24.000 - 60.317 Hz (Monitor: 59.000 - 61.000 Hz)
> + *
> + * Failures:
> + *
> + * Block 1, CTA-861 Extension Block:
> + * Video Capability Data Block: IT video formats are always underscanned, but bit 7 of Byte 3 of the CTA-861 Extension header is set to overscanned.
> + * EDID:
> + * CTA-861: Native progressive timings are a mix of several resolutions.
> + *
> + * EDID conformity: FAIL
> + *
> + * ================
> + *
> + * InfoFrame of '/sys/kernel/debug/dri/1/HDMI-A-1/infoframes/audio' was empty.
> + *
> + * ================
> + *
> + * edid-decode InfoFrame (hex):
> + *
> + * 82 02 0d 31 12 28 04 00 00 00 00 00 00 00 00 00
> + * 00
> + *
> + * ----------------
> + *
> + * HDMI InfoFrame Checksum: 0x31
> + *
> + * AVI InfoFrame
> + * Version: 2
> + * Length: 13
> + * Y: Color Component Sample Format: RGB
> + * A: Active Format Information Present: Yes
> + * B: Bar Data Present: Bar Data not present
> + * S: Scan Information: Composed for an underscanned display
> + * C: Colorimetry: No Data
> + * M: Picture Aspect Ratio: 16:9
> + * R: Active Portion Aspect Ratio: 8
> + * ITC: IT Content: No Data
> + * EC: Extended Colorimetry: xvYCC601
> + * Q: RGB Quantization Range: Limited Range
> + * SC: Non-Uniform Picture Scaling: No Known non-uniform scaling
> + * YQ: YCC Quantization Range: Limited Range
> + * CN: IT Content Type: Graphics
> + * PR: Pixel Data Repetition Count: 0
> + * Line Number of End of Top Bar: 0
> + * Line Number of Start of Bottom Bar: 0
> + * Pixel Number of End of Left Bar: 0
> + * Pixel Number of Start of Right Bar: 0
> + *
> + * ----------------
> + *
> + * AVI InfoFrame conformity: PASS
> + *
> + * ================
> + *
> + * edid-decode InfoFrame (hex):
> + *
> + * 81 01 05 49 03 0c 00 20 01
> + *
> + * ----------------
> + *
> + * HDMI InfoFrame Checksum: 0x49
> + *
> + * Vendor-Specific InfoFrame (HDMI), OUI 00-0C-03
> + * Version: 1
> + * Length: 5
> + * HDMI Video Format: HDMI_VIC is present
> + * HDMI VIC 1: 3840x2160 30.000000 Hz 16:9 67.500 kHz 297.000000 MHz
> + *
> + * ----------------
> + *
> + * Vendor-Specific InfoFrame (HDMI), OUI 00-0C-03 conformity: PASS
> + *
> + * ================
> + *
> + * InfoFrame of '/sys/kernel/debug/dri/1/HDMI-A-1/infoframes/hdr_drm' was empty.
> + *
> + * ================
> + *
> + * edid-decode InfoFrame (hex):
> + *
> + * 83 01 19 93 42 72 6f 61 64 63 6f 6d 56 69 64 65
> + * 6f 63 6f 72 65 00 00 00 00 00 00 00 09
> + *
> + * ----------------
> + *
> + * HDMI InfoFrame Checksum: 0x93
> + *
> + * Source Product Description InfoFrame
> + * Version: 1
> + * Length: 25
> + * Vendor Name: 'Broadcom'
> + * Product Description: 'Videocore'
> + * Source Information: PC general
> + *
> + * ----------------
> + *
> + * Source Product Description InfoFrame conformity: PASS
> + *
> * Testing
> * ~~~~~~~
> *
> * The helpers have unit testing and can be tested using kunit with:
> *
>

Note that the InfoFrame checks are still rudimentary for the AVI and HDMI InfoFrames.

It's on my TODO list to improve this further, but -ENOTIME :-(

Regards,

Hans

Next message: Benno Lossin: "Re: [PATCH v10 07/13] rust: hrtimer: implement `UnsafeHrTimerPointer` for `Pin<&T>`"
Previous message: Andreas Hindborg: "Re: [PATCH v10 01/13] rust: hrtimer: introduce hrtimer support"
In reply to: Maxime Ripard: "[PATCH 2/2] drm/display: hdmi: Mention Infoframes testing with edid-decode"
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