Created attachment 130176 [details] drm.debug=14 debug log I've recently obtained a DisplayPort monitor with audio (LG 34UM88) which I'm driving from a Dell E7240 (i5-4300U/Haswell) in a Dell E-Dock. Under Windows the audio output via the dock DisplayPort connector to the monitor works fine. Under Linux 4.10 there is no sign of the monitor existing as an audio device. Reading Bug#89895 suggests this support should be present in 4.11-rc1 so I upgraded to that to test. This is better, in that the DisplayPort audio device appears (all the way up to GNOME Sound settings offering me a "HDMI/DisplayPort 2" option), but at most I hear a brief piece of static when I first try to access the device and then nothing at any point afterwards. I'm not quite sure what information is relevant to provide in this report; I see mentions of trying drm-tip and/or booting with drm.debug=14. There don't appear to be any audio related changed in drm-tip post -rc1 but I've attached the debug log - 361.002037 is about the time after boot when I tried audio output via the DisplayPort device. Distro, if it makes a difference, is Debian/Stretch. libdrm 2.4.74, xorg 7.7 using the modesetting driver. # uname -a Linux mixian 4.11.0-rc1 #3 SMP Sun Mar 12 17:44:13 GMT 2017 x86_64 GNU/Linux # ls -1 /proc/asound/card0 codec#0 eld#0.0 eld#0.1 eld#0.2 eld#0.3 eld#0.4 eld#0.5 eld#0.6 eld#0.7 eld#0.8 id pcm10p pcm3p pcm7p pcm8p pcm9p # grep "" /proc/asound/card0/eld#0.* /proc/asound/card0/eld#0.0:monitor_present 0 /proc/asound/card0/eld#0.0:eld_valid 0 /proc/asound/card0/eld#0.1:monitor_present 0 /proc/asound/card0/eld#0.1:eld_valid 0 /proc/asound/card0/eld#0.2:monitor_present 0 /proc/asound/card0/eld#0.2:eld_valid 0 /proc/asound/card0/eld#0.3:monitor_present 1 /proc/asound/card0/eld#0.3:eld_valid 1 /proc/asound/card0/eld#0.3:monitor_name LG ULTRAWIDE /proc/asound/card0/eld#0.3:connection_type DisplayPort /proc/asound/card0/eld#0.3:eld_version [0x2] CEA-861D or below /proc/asound/card0/eld#0.3:edid_version [0x3] CEA-861-B, C or D /proc/asound/card0/eld#0.3:manufacture_id 0x6d1e /proc/asound/card0/eld#0.3:product_id 0x76e4 /proc/asound/card0/eld#0.3:port_id 0x0 /proc/asound/card0/eld#0.3:support_hdcp 0 /proc/asound/card0/eld#0.3:support_ai 0 /proc/asound/card0/eld#0.3:audio_sync_delay 0 /proc/asound/card0/eld#0.3:speakers [0x1] FL/FR /proc/asound/card0/eld#0.3:sad_count 1 /proc/asound/card0/eld#0.3:sad0_coding_type [0x1] LPCM /proc/asound/card0/eld#0.3:sad0_channels 2 /proc/asound/card0/eld#0.3:sad0_rates [0xc0] 44100 48000 /proc/asound/card0/eld#0.3:sad0_bits [0xe0000] 16 20 24 /proc/asound/card0/eld#0.4:monitor_present 0 /proc/asound/card0/eld#0.4:eld_valid 0 /proc/asound/card0/eld#0.5:monitor_present 0 /proc/asound/card0/eld#0.5:eld_valid 0 /proc/asound/card0/eld#0.6:monitor_present 0 /proc/asound/card0/eld#0.6:eld_valid 0 /proc/asound/card0/eld#0.7:monitor_present 0 /proc/asound/card0/eld#0.7:eld_valid 0 /proc/asound/card0/eld#0.8:monitor_present 0 /proc/asound/card0/eld#0.8:eld_valid 0
Weirdly, after a reboot to get rid of the drm.debug parameter, sound is now working. I don't believe I did anything different than the other 2 boots into 4.11-rc1 but let me know if there's any further information I can collect.
(In reply to Jonathan McDowell from comment #1) > Weirdly, after a reboot to get rid of the drm.debug parameter, sound is now > working. I don't believe I did anything different than the other 2 boots > into 4.11-rc1 but let me know if there's any further information I can > collect. Can you retry one more time with drm.debug parameter back in command line to see if you can reproduce again?
I've tried again with drm.debug=14 and a couple of boots from power-off in case something had got left setup. No joy reproducing however so I'm a bit stumped as to what went wrong when it wasn't working. Happy for the bug to be closed and if I manage to reproduce I can re-open.
(In reply to Jonathan McDowell from comment #3) > I've tried again with drm.debug=14 and a couple of boots from power-off in > case something had got left setup. No joy reproducing however so I'm a bit > stumped as to what went wrong when it wasn't working. Happy for the bug to > be closed and if I manage to reproduce I can re-open. Thanks Jonathan for your retry and feedback. I am closing for now the but but don't hesitate to reopen it if it is occurring again.
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