drm/i915/dp: add lane_count check in intel_dp_check_link_status
Currently it's entirely possible to go through the link training step without first determining the lane_count, which is silly since we end up doing a bunch of aux transfers of size = 0, as highlighted by WARN_ON(!msg->buffer != !msg->size), and can only ever result in a 'failed to update link training' message. This can be observed during intel_dp_long_pulse where we can do the link training step, but before we have had a chance to set the link params. To avoid this we add an extra check for the lane_count in intel_dp_check_link_status, which should prevent us from doing the link training step prematurely. v2: add WARN_ON_ONCE and FIXME comment (Ville) References: https://bugs.freedesktop.org/show_bug.cgi?id=97344 Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> Cc: Mika Kahola <mika.kahola@intel.com> Signed-off-by:Matthew Auld <matthew.auld@intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/1476912593-10019-1-git-send-email-matthew.auld@intel.comSigned-off-by:
Ville Syrjälä <ville.syrjala@linux.intel.com>
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