Hi, I hope this is the right section to report this bug; if not, please redirect me to the appropriate one. I am having trouble getting audio via HDMI/DP working. My setup has a Thinkpad Ultra dock which has a Synaptics DP MST hub connected to a Dell U2415 monitor via DP. `aplay -l' reports: **** List of PLAYBACK Hardware Devices **** card 0: HDMI [HDA Intel HDMI], device 3: HDMI 0 [HDMI 0] Subdevices: 0/1 Subdevice #0: subdevice #0 card 0: HDMI [HDA Intel HDMI], device 7: HDMI 1 [HDMI 1] Subdevices: 1/1 Subdevice #0: subdevice #0 card 0: HDMI [HDA Intel HDMI], device 8: HDMI 2 [HDMI 2] Subdevices: 1/1 Subdevice #0: subdevice #0 card 1: PCH [HDA Intel PCH], device 0: ALC3232 Analog [ALC3232 Analog] Subdevices: 0/1 Subdevice #0: subdevice #0 So, the cards are being detected correctly. However, I do not see that the monitor is being detected as connected as per ELD, even though I could use the monitor for video. $ ls -1 /proc/asound/card0 codec#0 eld#0.0 eld#0.1 eld#0.2 id pcm3p pcm7p pcm8p $ cat /proc/asound/card0/eld* monitor_present 0 eld_valid 0 monitor_present 0 eld_valid 0 monitor_present 0 eld_valid 0 Could it be that the DP MST Hub in the dock is misbehaving or not transmitting ELD? If so, how can I verify that?
It would help considerably if you indicated which kernel version you're running. Please attach dmesg with drm.debug=14 module parameter set, from boot to trying to use audio.
It is a known issue that audio does not work with DP-MST at the moment. Dave didn't get as far as figuring out the audio transport side of MST...
(In reply to Chris Wilson from comment #2) > It is a known issue that audio does not work with DP-MST at the moment. Dave > didn't get as far as figuring out the audio transport side of MST... Is this still the case? If so, is the root issue independent of the audio driver side, but rather a drm generic MST implementation issue?
CC Dave.
http://mid.gmane.org/CAPM=9tyc70Xd4us2LFCCYNYT8MfgqNKFxG-f=Ne7dJ_cVNYjXw@mail.gmail.com
I'm having the same problem, starting with Linux Kernel commit 0e32b39c ("drm/i915: add DP 1.2 MST support (v0.7)") and continuing through at least Linux 4.0.1, the latest kernel I've tried. I'm attaching my dmesg output with my 4.0.1-gentoo kernel build with drm.debug=14 on the kernel command line.
Created attachment 115719 [details] Kernel dmesg output for 4.0.1-gentoo with "drm.debug=14"
As Jani pointed out, I've done initial enablement http://cgit.freedesktop.org/~airlied/linux/log/?h=dp-mst-audio though the audio developers are quiet and the hardware seems to have some strange behaviour.
I see you keep rebasing your DP audio fixes, any luck with the audio developers? It would be really nice to get this upstream.
Just a quick update that Dave's five patches in the git repo below, on top of the Gentoo 4.1.2 (sys-kernels/gentoo-sources-4.1.2) appear to work correctly for me after some quick testing.
*** Bug 90531 has been marked as a duplicate of this bug. ***
DP audio has been enabled on i915[1]. Please create a new bug if there are problems with it. [1] commit 7f9e77545b92bcb894b8e2be5646535e8ba8da9e Author: Libin Yang <libin.yang@intel.com> Date: Mon Nov 28 20:07:07 2016 +0800 drm/i915: enable dp mst audio This patch adds support for DP MST audio in i915.
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