hdmi out

Barry Vercoe barry at laptop.org.au
Sun Aug 18 01:05:14 EDT 2013

OK, with tail -f ... messages, I do see a burst of messages and the 
projector shows the exact screen.  But only for 15 seconds, when the 
projector then goes blank and reverts to _No Signal_ until I touch 
something on the XO like the screen, track pad or some key.  Apparently 
the XO has stopped sending hdmi signals, so the projector is reporting 
exactly that.

Is this the XO hdmi port going to sleep?  And do I have control over 
some time constant?
Or perhaps my projector is going blank when it sees no recent activity 
on the port.  Might it be expecting at least a screen refresh over the 
hdmi channel?  I don't have a projector manual that would describe that ...
It seems I can jiggle the HDMI cable a fair bit without issue, so I 
think the physical connection is sound.
Just not clear on who is exercising the time constant in between 
gestures to the XO.

-- b

On 18/08/2013 4:00 p.m., Tom Parker wrote:
> On 18/08/13 15:01, Barry Vercoe wrote:
>> Tom, attached is a file dmesg.output. Sending just to you since I didn't
>> understand what mailing list you meant.
> olpc-devel, Jon Nettleton who was involved with the HDMI code is 
> monitoring that list. I've copied them in and re-attached your dmesg 
> output.
>> It may well be a problem with my micro-to-standard hdmi cable, since I
>> don't hear a click when I plug it in.  The cable is a Pudney P594 Type A
>> plug to Type D plug, think from Dick Smith (no one else seemed to have
>> one ...).
> The click is a mechanical one and quite faint and doesn't always 
> happen. Sometimes you feel it with your fingers rather than hear it.
> I have this one http://www.pbtech.co.nz/index.php?z=p&p=CABDNX8018 and 
> they also have 2m versions and an adaptor which might be more 
> appropriate if it is what I think it is (there's no picture). With an 
> adaptor the school would need to supply a regular HDMI cable rather 
> than a female-female adaptor and a cable -- whatever length you supply 
> will be too short).
>> Tell me if you don't see the connection in dmesg.  Perhaps a razor blade
>> to the connector will get it further in till I hear a click (is that
>> audio out, or physical?)
> It's obviously doing something -- you can see the HDMI system start 
> and select 1080p:
> [   88.056712] Using config for 1920x1080 CEA
> This is the last 4 lines you quoted:
> [   88.069656] hdmi_video_cfg: I have auto-learned the video frame format
> [   88.076560] ++++++++++++ hdmi_hpd_work state 0 hdmi_state 1
> [   88.992348] work_launch
> [   88.992400] ++++++++++++ hdmi_hpd_work state 4000 hdmi_state 0
> I see the first two of those, but not the second two.
> I wonder if you have a bad connection? Try pressing the cable into the 
> socket and holding it there.
> You can watch the output of this log in real time by typing the 
> following into terminal:
> tail -f /var/log/messages
> It should show you the last few lines of the the log and then print 
> out any new log messages. You should see a burst of messages when you 
> plug the cable in.

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