** Description changed: - Steps: - 1. Install manifest and boot into OS - 2. Connect an external monitor via HDMI port - 3. Check sound setting + This bug comes from the OEM project, and the engineer Jim Qu from AMD took + almost 2 weeks to investigate this problem, then he worte these two patches to + fix this problem and now the patches are merged to sound repository. - Expected results: System should able to detect HDMI audio output + According to Jim Qu's investigation, the root cause of this problem is: + 1. there is two GPU on the system. iGPU has a audio codec for HDMI output, + and dGPU is without audio codec it is only for offload rendering. + 2. under runtime pm, when dGPU suspend, amdgpu will also call vgaswitchroo + driver to power off audio which vgaswitchroo client is VGA_SWITCHEROO_DIS. + 3. In current HDA audio driver, the iGPU's audio will register to vgaswitchroo + as VGA_SWITCHEROO_DIS, therefore, the audio will be selected and powered off + by runtime pm. - Actual results: System can't detect HDMI audio output + [Impact] + On the Dell Latitude 5495, If we plug a monitor with audio capability to the + HDMI/DP ports, we can't find HDMI/DP audio sinks as expected, then we can't + play any sound through HDMI/DP audio. - Failure rate: 2/2 + [Fix] + With these two patches, the driver will not always set vgaswicheroo clients of + HDA audio as VGA_SWITCHEROO_DIS, it will set it to _DIS or _IGD with the help + of callback function of DRM drivers. So on this machine, the vgaswicheroo client + will be set _IGD, then it will not be powered off when discrete gpu is powered off. + + [Test Case] + We tested plug/unplug detection and playback through HDMI/DP audio, everything works + well. + + [Regression Potential] + Very low, without these two patches, the vgaswitchroo client of audio will be + set to _DIS unconditionally, it did not expose any problem because in the past, + all the HDMI/DP audio codecs are in the discreate GPU. But on Latitude 5495, the + HDMI/DP audio codec is in the integrated GPU, so we need to change the driver to + let DRM driver decide if it is _DIS or _IGD, it will not introduce regression for + old mahcines on old machines, the client will be set to _DIS as before. + + And we have tested these two patches on some old machines with two gpus like A+A + , I+A and I+N, all of them worked well as before.
-- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1782689 Title: HDMI/DP audio can't work on the laptop of Dell Latitude 5495 To manage notifications about this bug go to: https://bugs.launchpad.net/hwe-next/+bug/1782689/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
