drm: Use spread spectrum when the bios tells us it's ok.

Lifted from the DDX modesetting.

Signed-off-by: Kristian Høgsberg <krh@redhat.com>
Signed-off-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 8 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/intel_bios.c b/drivers/gpu/drm/i915/intel_bios.c
index 4ca82a025525..65be30dccc77 100644
--- a/drivers/gpu/drm/i915/intel_bios.c
+++ b/drivers/gpu/drm/i915/intel_bios.c
@@ -135,6 +135,14 @@ parse_general_features(struct drm_i915_private *dev_priv,
         if (general) {
                 dev_priv->int_tv_support = general->int_tv_support;
                 dev_priv->int_crt_support = general->int_crt_support;
+                dev_priv->lvds_use_ssc = general->enable_ssc;
+
+                if (dev_priv->lvds_use_ssc) {
+                  if (IS_I855(dev_priv->dev))
+                    dev_priv->lvds_ssc_freq = general->ssc_freq ? 66 : 48;
+                  else
+                    dev_priv->lvds_ssc_freq = general->ssc_freq ? 100 : 96;
+                }
         }
 }