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drm/i915/dp: force eDP lane count to max available lanes on BDW
There are certain BDW high res eDP machines that regressed due to
commit 38aecea0cc
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date: Mon Mar 3 11:18:10 2014 +0100
drm/i915: reverse dp link param selection, prefer fast over wide again
The commit lead to 2 lanes at 5.4 Gbps being used instead of 4 lanes at
2.7 Gbps on the affected machines. Link training succeeded for both, but
the screen remained blank with the former config. Further investigation
showed that 4 lanes at 5.4 Gbps worked also.
The root cause for the blank screen using 2 lanes remains unknown, but
apparently the driver for a certain other operating system by default
uses the max available lanes. Follow suit on Broadwell eDP, for at least
until we figure out what is going on.
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=76711
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@gmail.com>
Tested-by: Rodrigo Vivi <rodrigo.vivi@gmail.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
This commit is contained in:
parent
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commit
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1 changed files with 6 additions and 1 deletions
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@ -810,7 +810,12 @@ intel_dp_compute_config(struct intel_encoder *encoder,
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bpp = dev_priv->vbt.edp_bpp;
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}
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if (dev_priv->vbt.edp_lanes) {
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if (IS_BROADWELL(dev)) {
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/* Yes, it's an ugly hack. */
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min_lane_count = max_lane_count;
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DRM_DEBUG_KMS("forcing lane count to max (%u) on BDW\n",
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min_lane_count);
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} else if (dev_priv->vbt.edp_lanes) {
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min_lane_count = min(dev_priv->vbt.edp_lanes,
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max_lane_count);
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DRM_DEBUG_KMS("using min %u lanes per VBT\n",
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