On Thu, May 31, 2012 at 1:08 PM, Chris Wilson <chris at chris-wilson.co.uk> wrote: > Whilst most monitors do wire up the HPD presence pin, it seems quite a > few KVM do not. Therefore if we simply rely on the HPD pin being > asserted to indicate a connected monitor we fail miserable, so fall back > to performing a DCC query for the EDID. This message is wrong though, the pin is a lie, there is no HPD pin on the standard VGA cable. VGA load detect is done by measuring the resistance across some pins, a lot of kvms use bad resistor values, should be 50Ohm, someone got some cheap 75Ohm from a TV or something. Dave. > > Reported-and-tested-by: Matthieu LAVIE <boiteamadmax at hotmail.com> > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=50501 > Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk> > --- > ?drivers/gpu/drm/i915/intel_crt.c | ? ?8 +++++--- > ?1 file changed, 5 insertions(+), 3 deletions(-) > > diff --git a/drivers/gpu/drm/i915/intel_crt.c b/drivers/gpu/drm/i915/intel_crt.c > index f0223d0..804611e 100644 > --- a/drivers/gpu/drm/i915/intel_crt.c > +++ b/drivers/gpu/drm/i915/intel_crt.c > @@ -453,13 +453,15 @@ intel_crt_detect(struct drm_connector *connector, bool force) > ? ? ? ?struct intel_load_detect_pipe tmp; > > ? ? ? ?if (I915_HAS_HOTPLUG(dev)) { > + ? ? ? ? ? ? ? /* We can not rely on the HPD pin always being correctly wired > + ? ? ? ? ? ? ? ?* up, for example many KVM do not pass it through, and so > + ? ? ? ? ? ? ? ?* only trust an assertion that the monitor is connected. > + ? ? ? ? ? ? ? ?*/ > ? ? ? ? ? ? ? ?if (intel_crt_detect_hotplug(connector)) { > ? ? ? ? ? ? ? ? ? ? ? ?DRM_DEBUG_KMS("CRT detected via hotplug\n"); > ? ? ? ? ? ? ? ? ? ? ? ?return connector_status_connected; > - ? ? ? ? ? ? ? } else { > + ? ? ? ? ? ? ? } else > ? ? ? ? ? ? ? ? ? ? ? ?DRM_DEBUG_KMS("CRT not detected via hotplug\n"); > - ? ? ? ? ? ? ? ? ? ? ? return connector_status_disconnected; > - ? ? ? ? ? ? ? } > ? ? ? ?} > > ? ? ? ?if (intel_crt_detect_ddc(connector)) > -- > 1.7.10 > > _______________________________________________ > Intel-gfx mailing list > Intel-gfx at lists.freedesktop.org > http://lists.freedesktop.org/mailman/listinfo/intel-gfx
