<html> <head> <base href="https://bugs.freedesktop.org/" /> </head> <body> <div> <a class="bz_bug_link bz_status_NEEDINFO " title="NEEDINFO - [BYT] Displayport signals stay on after monitor is unplugged" href="https://bugs.freedesktop.org/show_bug.cgi?id=95141#c8">Comment # 8</a> on <a class="bz_bug_link bz_status_NEEDINFO " title="NEEDINFO - [BYT] Displayport signals stay on after monitor is unplugged" href="https://bugs.freedesktop.org/show_bug.cgi?id=95141">bug 95141</a> from <a class="email" href="mailto:sarvatt@gmail.com" title="roberth <sarvatt@gmail.com>"> roberth</a> <pre>(In reply to Manasi from <a href="show_bug.cgi?id=95141#c7">comment #7</a>) > In order to reproduce the bug, I did some PHY testing here on my system with > drm-intel-nightly (kernel 4.6.0-rc4). I hooked up the HPD and data lines to > the oscilloscope to see the signal levels after the DP monitor is > disconnected. And I saw that signal levels were as low as -1mv after the DP > monitor is disconnected. Also the HPD signal is 0V DC on the DP disconnect. > So I am not able to reproduce the issue that you are seeing. > For me to root cause this bug, I would need the following information from > you: > - Could you also hook up the data signals to the oscilloscope and verify if > there is any signal on those lines after the DP monitor is disconnected. I do not have an oscilloscope to verify, I'm just using a voltmeter and it was showing signals on after unplugging DP from what I saw. I can see if the customer does if that would help though? > - From the data you provided, it is strange that the HPD signal is 3.29V on > boot. Was this system booted with DP connected? How did you measure this > electrical signal level? I am plugging in a dp cord and measuring it on the pins there with a voltmeter with one end on the plug case and the other on the pin. Would that make it give false results? I have been unable to measure directly on the displayport connector on the machine because it is so small, but I will try again if so. > - If the DP is not connected on boot and you plug it in later, does the DP > monitor display it properly and it works? Yeah that works fine, and there are no excess emissions in that case according to their testing also. > - Could you send separate dmesg logs for : > Boot without DP connected > Then dmesg -c to clear dmesg > Plug in DP cable and collect logs > dmesg -c > Unplug and collect logs This is what I posted in comments 1-3, but I did it again on 4.4.0 and will attach those. drm-intel-nightly and drm-intel-next both do not work on this machine, no displays ever get brought up including the internal one. Would logs from 4.6.0-rc6 be acceptable? What drm.debug level would be most helpful? > - Please send the picture of the motherboard to see the connections of the > HPD pin on the motherboard. Also send us the schematics of the same if you > have. Will do ASAP, I will ask for schematics as well to forward them.</pre> </div> <hr> You are receiving this mail because: <ul> <li>You are on the CC list for the bug.</li> <li>You are the QA Contact for the bug.</li> <li>You are the assignee for the bug.</li> </ul> </body> </html>