Created attachment 113426 [details] VBIOS with stock nouveau from kernel 3.19.0-1.fc22.x86_64 this nva8 came with a thinkpad t410 my pstate file looks like this: 03: core 135 MHz shader 270 MHz memory 135 MHz 07: core 405 MHz shader 810 MHz memory 405 MHz 0f: core 606 MHz shader 1468 MHz memory 790 MHz AC: core 405 MHz shader 810 MHz memory 405 MHz when clocking to 07 or 0f everything works. however, when clocking to pstate=03 i get constant flickering (maybe <5-10 hz), although the clocks do change, and nothing crashes. (i can change clocks back to 07 or 0f with no more flickering) vbios attached mmiodump where i fumbled around with powermizer while the blob reclocked (no second monitor attached): https://www.dropbox.com/s/jjh6hpcix1swc7r/mmiotrace.log?dl=0
there are no additional kernel messages when reclocking as well
Created attachment 113430 [details] PFB region peeks for pstate 07
(In reply to C, Zhang from comment #0) > however, when clocking to pstate=03 i get constant flickering (maybe <5-10 > hz) Flickering at low clocks is expected and is most likely due to hardware constraints - memory not being quick enough to deal with the additional screen, hence no flickering at higher clock - rather than a driver bug. Look in nvidia-settings which clocks the blob sets when you plug your external screen in: most likely it will automatically go from level 03 to level 07 and won't go back to 03 unless you unplug the external screen. See "Blank monitor, flicker, snow, or other random live image corruption" at http://nouveau.freedesktop.org/wiki/TroubleShooting/#index8h3.
Right. That makes a lot of sense; unplugging an external monitor fixes the issue. I guess it's just a hardware limitation then. The blob does indeed avoid 03 with an extra monitor attached. Thanks for the help! That'd be another thing to worry about if dynamic power scaling were ever implemented for nouveau then.
Closing this bug report as NOTABUG. Feel free to reopen it if we forget about hardware limitations when adding support for dynamic reclocking!
Use of freedesktop.org services, including Bugzilla, is subject to our Code of Conduct. How we collect and use information is described in our Privacy Policy.