Created attachment 141929 [details]
If I enable psr with i915.enable_psr=1 the syslog is flooded by the message below and the screen blanks intermittently for a second or so.
*ERROR* [CONNECTOR:65:eDP-1] Link Training failed at link rate = 270000, lane count = 2
No such message is logged when psr is disabled and no flashing occurs.
This is on a Thinkpad T450s, Core i5-5300U, kernel 4.19.0-rc6, Arch Linux.
Created attachment 141930 [details]
PSR on BDW isn't supported currently.
But, here's something you can try on top of drm-tip (https://cgit.freedesktop.org/drm-tip) https://patchwork.freedesktop.org/series/50654/
As documentation for future BDW enablement, it'd be great if you also attach the output of
edid-decode /sys/class/drm/card0-eDP-1/edid and /sys/kernel/debug/dri/0/i915_edp_psr_status
Created attachment 141941 [details]
Created attachment 141942 [details]
With drm-tip and your patches the errors are gone, but the flashing still occurs albeit very occasionally. I guess PSR is still inactive on Broadwell though.
Do you know if this platform is supposed to reach PC10? All I could get to is PC7, maybe due to lack of PSR support?
Could you attach dmesg logs when running with the drm-tip & patches? Please don't forget to increase the log level(drm.debug=0x1e).
Created attachment 141964 [details]
dmesg log (drm-tip + patches)
There is a lot of short pulses from your eDP but no PSR or other errors detected.
Before you dump this log did you got any flashing?
no flashing before this dump. There is some flashing after the first time the display comes back from blanking for inactivity. I'll try and capture a new dmesg when flashing occurs
So, this time the screen didn't come back from blanking. I had to force reboot. journalctl -b -1 attached. There's an *ERROR* [CRTC:39:pipe A] flip_done timed out
Created attachment 141965 [details]
log of screen locking after blanking
The problem is '*ERROR* [CRTC:39:pipe A] flip_done timed out' but there is no clue of what caused that in your logs.
Try to reproduce with this kernel parameters: drm.debug=0x1e log_buf_len=4M
Hum this may not be 100% related to PSR and there is reports of flip_done timeout with PSR disabled too in BDW: