• Ville Syrjälä's avatar
    drm/i915: Register shadow VGA even when it produces spurious detection results · f0dfb1a8
    Ville Syrjälä authored
    Having a shadow VGA connector is useful for testing purposes. We
    currently skip registering the connector on machines where the
    CRT detect falsely reports it as connected. Let's instead move the
    the blacklist check to the detect callback (and hpd setup) and
    if we get a match we always report the connector as disconnected.
    This way we get a shadow VGA connector to help with testing, while
    we still avoid the user facing problems from the incorrect
    detection results.
    
    commit 8ca4013d ("CHROMIUM: i915: Add DMI override to skip CRT
    initialization on ZGB") doesn't provide much in the way of details
    as to why 'ACER ZGB' was added to the blacklist. Trying to trace it
    further leads me to a chromeos bugreport I can't access. So based on
    the fact that the commit added the
    "/* Skip machines without VGA that falsely report hotplug events */"
    comment, I'm going to assume that it was just spurious CRT detection.
    So it should be safe to move the blacklist to just block the detection
    and hpd without causing a regression on said machine.
    
    In fact Stéphane confirmed on irc that the problem was indeed just
    crappy hotplug detect:
    "22:29 < marcheu> vsyrjala: the port isn't there, but the load detect is
     improperly stubbed in hw
     22:29 < marcheu> vsyrjala: so it floats"
    so this change should be perfectly fine.
    
    v2: Add irc quote from Stéphane
    
    Cc: Duncan Laurie <dlaurie@chromium.org>
    Cc: Olof Johansson <olofj@chromium.org>
    Cc: Stéphane Marchesin <marcheu@chromium.org>
    Signed-off-by: default avatarVille Syrjälä <ville.syrjala@linux.intel.com>
    Link: http://patchwork.freedesktop.org/patch/msgid/1474881646-1326-2-git-send-email-ville.syrjala@linux.intel.comReviewed-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
    f0dfb1a8
intel_crt.c 26 KB