[Differential] [Request, 3 lines] D2336: update CRTCs before enabling an output

[sebas (Sebastian Kügler)]

sebas created this revision.
sebas added a reviewer: dvratil.
sebas added a subscriber: Plasma.
Restricted Application added a project: Plasma.
Restricted Application added a subscriber: plasma-devel.

REVISION SUMMARY
  When connecting the docking station (Lenovo OneLink+), which has a VGA
  connected monitor attached, enabling a display usually fails. It
  complains about no CRTC being available (and indeed the available CRTCs
  don't have our output as possible output). Updating the CRTC before
  enabling an output makes this work for me.
  
  Note: it's not a problem when connecting via HDMI, this seems to be
  either unique to VGA or to the docking station. (Other dock users report
  similar behaviour).
  
  I'm being fairly liberal with update calls here, probably just doing it
  in enableOutput will work as well -- but I haven't extensively tested
  it. I don't know how expensive these calls are.
  
  On boot, my setup is still not restored, but at least with this patch
  manually enabling an output works reliably now.
  
  BUG:366346

TEST PLAN
  - rebooted with dock disconnected, can enable an output with this patch, would reliably fail without
  - rebooted with dock connected, still works
  - connected/disconnected/connected dock with output attached, works well

REPOSITORY
  rLIBKSCREEN KScreen Library

BRANCH
  sebas/crtcupdate

REVISION DETAIL
  https://phabricator.kde.org/D2336

AFFECTED FILES
  backends/xrandr/xrandrconfig.cpp
  backends/xrandr/xrandrcrtc.cpp

EMAIL PREFERENCES
  https://phabricator.kde.org/settings/panel/emailpreferences/

To: sebas, dvratil
Cc: plasma-devel, #plasma, ali-mohamed, jensreuterberg, abetts, sebas
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