I found a potential bug for i915 regarding to ELD parsing.
I was trying to monitor ELD by watching "/proc/asound/card0/eld#3.0" and I realized that the ELD might failed to read from HDMI when AC power is not plugged.
I am also looking for the right place to file the bug, please suggest.
00:02.0 VGA compatible controller: Intel Corporation Ivy Bridge Graphics Controller (rev 05)
00:14.0 USB controller: Intel Corporation Panther Point USB xHCI Host Controller (rev 04)
00:16.0 Communication controller: Intel Corporation Panther Point MEI Controller #1 (rev 04)
00:1a.0 USB controller: Intel Corporation Panther Point USB Enhanced Host Controller #2 (rev 04)
00:1b.0 Audio device: Intel Corporation Panther Point High Definition Audio Controller (rev 04)
00:1c.0 PCI bridge: Intel Corporation Panther Point PCI Express Root Port 1 (rev c4)
00:1c.1 PCI bridge: Intel Corporation Panther Point PCI Express Root Port 2 (rev c4)
00:1d.0 USB controller: Intel Corporation Panther Point USB Enhanced Host Controller #1 (rev 04)
00:1f.0 ISA bridge: Intel Corporation Panther Point LPC Controller (rev 04)
00:1f.2 RAID bus controller: Intel Corporation 82801 Mobile SATA Controller [RAID mode] (rev 04)
00:1f.3 SMBus: Intel Corporation Panther Point SMBus Controller (rev 04)