HDMI TV connected via USB-C-To-HDMI (hoho) dongle not recognized |
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Issue descriptionI got a Soraka running a simplechrome 66.0.3329.0 on a CrOs 10362.0, and I'm connecting an external TV (QN55Q7FAMFXZA -- Samsung Q Series QN55Q7FAMF - 55" QLED Smart TV - 4K UltraHD) using the HDMI-to-USB-C connector we got in go/stuff. The external TV is not recognized, i.e. the name is "unknown display" and the modes available are maxed out at 1024x768. Attached the dmesg and modetest files before and after connecting the dongle, and the gpu info for good measure.
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Feb 7 2018
Monorail doesn't like my gpu.mhtml --> uploading a pdf then.
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Feb 7 2018
the root cause is that we are unable to read the EDID: [ 84.384623] [drm:drm_edid_block_valid] *ERROR* EDID checksum is invalid, remainder is 40 [ 84.384636] Raw EDID: [ 84.384642] 00 ff ff ff ff ff ff 00 4c 2d e1 0d 00 0e 00 01 [ 84.384647] 01 1b 01 03 ff ff ff ff ff ff ff ff ff ff ff ff [ 84.384651] ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff [ 84.384655] ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff [ 84.384659] ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff [ 84.384663] ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff [ 84.384667] ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff [ 84.384671] ff ff ff ff ff ff ff ff ff ff ff ff ff ff 03 ff IIRC usually 0xff happens when the voltage on the DDC or aux channel doesn't swing far enough to result in a usable signal. Of course if would be nice to know which side of the dongle has the issue (whether the bridge chip already gets a bad EDID, or if that's only over DP).
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Feb 7 2018
I'd recommend trying both ports (looks like failure was for port1) [ 122.370578] PDLOG 2018/02/07 21:12:38.1518037957 P1 HDMI info: family:0010 chipid:2850 irom:2.1.0 fw:0.74.0 Also both orientations (USBC cable flipped or normal) to further refine the repro. Has this dongle + HDMI + TV combo worked on a different laptop before? Has the Soraka on port1 connected to some other external display worked previously?
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Feb 7 2018
I tried: both ports, with two different models of the same HDMI dongle (procured at different times from techstop), with two different HDMI cables. Also, for good measure, on an Eve. None of the combinations worked. The TV works, as I also have a guado, connected via direct HDMI and the resolution is fine.
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Feb 12 2018
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Feb 12 2018
Sounds like an issue with hoho specifically, over to tbroch@ for triage
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Feb 16 2018
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Nov 16
Sounds like this is long-pole issue specific to TV (QN55Q7FAMFXZA) + dongle (hoho). @mcasas would you have cycles to debug with a 'hoho in dev-mode'? Alternatively, need to locate same TV on the west coast or another report of similar failure so I can debug. |
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