[Bug 93782] [i9xx TV][BISECT] vblank wait timeout on crtc

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=93782

--- Comment #26 from Mariusz Mazur <mariusz.g.mazur at gmail.com> ---
Ah, progress, thanks for that. Based on your comment I've snooped around the
code, and found this in drivers/gpu/drm/i915/intel_tv.c:

    /* For unknown reasons the hw barfs if we don't do this vblank wait. */
    intel_wait_for_vblank(dev, intel_crtc->pipe);

along with the commit log for it (bf2125e2f7e931b50a6c76ba0435ba001409ccbf):

    drm/i915: wait for a vblank to pass after tv detect

    Otherwise the hw will get confused and result in a black screen.

    (…)

    v2: As suggested by Chris Wilson, add a small comment to ensure that
    no one accidentally removes this vblank wait again - there really
    seems to be no sane explanation for why we need it, but it is
    required.

Which leads me to believe that if I figure out a few places in the code to
sprinkle intel_wait_for_vblank() calls, it might fix the issue. I'll get my
lucky dice and get right to it.

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