drm/i915: Fix eDP low vswing for Broadwell

BugLink: http://bugs.launchpad.net/bugs/1580754
commit 992e7a41f9fcc7bcd10e7d346aee5ed7a2c241cb upstream.

It was noticed on bug #94087 that module parameter
i915.edp_vswing=2 that should override the VBT setting
to use default voltage swing (400 mV) was not applied
for Broadwell.

This patch provides a fix for this by checking if default
i.e. higher voltage swing is requested to be used and
applies the DDI translations table for DP instead of eDP
(low vswing) table.

v2: Combine two if statements into one (Jani)
v3: Change dev_priv->edp_low_vswing to use dev_priv->vbt.edp.low_vswing

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=94087
Signed-off-by: Mika Kahola <mika.kahola@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1461155942-7749-1-git-send-email-mika.kahola@intel.com
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
(cherry picked from commit 00983519214b61c1b9371ec2ed55a4dde773e384)
[Jani: s/dev_priv->vbt.edp.low_vswing/dev_priv->edp_low_vswing/ to backport]
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>

diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
index 241252de71864ef2c6274bb5926dd9239bccc472..3c6b07683bd901d98cd070759c528b35b335bdac 100644 (file)
--- a/drivers/gpu/drm/i915/intel_ddi.c
+++ b/drivers/gpu/drm/i915/intel_ddi.c
@@ -464,9 +464,17 @@ static void intel_prepare_ddi_buffers(struct drm_device *dev, enum port port,
        } else if (IS_BROADWELL(dev)) {
                ddi_translations_fdi = bdw_ddi_translations_fdi;
                ddi_translations_dp = bdw_ddi_translations_dp;
-               ddi_translations_edp = bdw_ddi_translations_edp;
+
+               if (dev_priv->edp_low_vswing) {
+                       ddi_translations_edp = bdw_ddi_translations_edp;
+                       n_edp_entries = ARRAY_SIZE(bdw_ddi_translations_edp);
+               } else {
+                       ddi_translations_edp = bdw_ddi_translations_dp;
+                       n_edp_entries = ARRAY_SIZE(bdw_ddi_translations_dp);
+               }
+
                ddi_translations_hdmi = bdw_ddi_translations_hdmi;
-               n_edp_entries = ARRAY_SIZE(bdw_ddi_translations_edp);
+
                n_dp_entries = ARRAY_SIZE(bdw_ddi_translations_dp);
                n_hdmi_entries = ARRAY_SIZE(bdw_ddi_translations_hdmi);
                hdmi_default_entry = 7;