This week I tried HDMI again on my system, and noticed it was completely broken.
Got just no signal on my screen.
I knew it was working some months (and upgrades) ago.
After testing I found out the issue was introduced between kernel v3.14 and v3.15.
Insert HDMI cable into my laptop, and no signal on the external display.
The dmesg fills with errors also:
[ 186.210622] nouveau E[ PDISP][0000:01:00.0] INVALID_STATE [UNK08] chid 0 mthd 0x0080 data 0x00000000
[ 186.210627] nouveau E[ PDISP][0000:01:00.0] Core:
[ 186.210634] nouveau E[ PDISP][0000:01:00.0] 0x0084: 0x5dc34da1 -> 0x80000000
[ 186.210640] nouveau E[ PDISP][0000:01:00.0] 0x0088: 0x00000000
After some git bisect playtime, I found out the following commit caused the issue:
So I went back to stable 3.16 (Ubuntu Utopic version), and did a git revert for that commit.
And yep, HDMI output was working again, and no more nouveau errors in dmesg.
[ 30.823267] nouveau [ DEVICE][0000:01:00.0] BOOT0 : 0x0c1a00a1
[ 30.823269] nouveau [ DEVICE][0000:01:00.0] Chipset: GF108 (NVC1)
[ 30.823270] nouveau [ DEVICE][0000:01:00.0] Family : NVC0
Laptop dell xps 15 l502x
Created attachment 106697 [details]
Attached a full dmesg.
The last lines are when I stop lightdm, and runpm stops the nvidia card.
This also causes shutdown to hang.
Seems like Ben fixed this issue:
Used that commit on my kernel, and it fixes the issue!