A broken conditional would lead to SDVOC waiting upon hotplug events on
SDVOB - and so miss all activity on its SDVO port.
This regression has been introduced in
commit 
1d843f9de4e6dc6a899b6f07f106c00da09925e6
Author: Egbert Eich <eich@suse.de>
Date:   Mon Feb 25 12:06:49 2013 -0500
    DRM/I915: Add enum hpd_pin to intel_encoder.
References: https://bugs.freedesktop.org/show_bug.cgi?id=58405
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
[danvet: Add regression note.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
 
        /* Only enable the hotplug irq if we need it, to work around noisy
         * hotplug lines.
         */
-       if (intel_sdvo->hotplug_active)
-               intel_encoder->hpd_pin = HPD_SDVO_B ? HPD_SDVO_B : HPD_SDVO_C;
+       if (intel_sdvo->hotplug_active) {
+               intel_encoder->hpd_pin =
+                       intel_sdvo->is_sdvob ?  HPD_SDVO_B : HPD_SDVO_C;
+       }
 
        intel_encoder->compute_config = intel_sdvo_compute_config;
        intel_encoder->disable = intel_disable_sdvo;