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>

3 files changed, 24 insertions, 6 deletions

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 7325363164f..135a08f615c 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -184,6 +184,8 @@ typedef struct drm_i915_private {
         unsigned int lvds_dither:1;
         unsigned int lvds_vbt:1;
         unsigned int int_crt_support:1;
+        unsigned int lvds_use_ssc:1;
+        int lvds_ssc_freq;
 
         struct drm_i915_fence_reg fence_regs[16]; /* assume 965 */
         int fence_reg_start; /* 4 if userland hasn't ioctl'd us yet */
diff --git a/drivers/gpu/drm/i915/intel_bios.c b/drivers/gpu/drm/i915/intel_bios.c
index 4ca82a02552..65be30dccc7 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;
+                }
         }
 }
 
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 8b203870626..13f9b6667c9 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -217,7 +217,7 @@ bool intel_pipe_has_type (struct drm_crtc *crtc, int type)
     return false;
 }
 
-#define INTELPllInvalid(s)   { /* ErrorF (s) */; return false; }
+#define INTELPllInvalid(s)   do { DRM_DEBUG(s); return false; } while (0)
 /**
  * Returns whether the given set of divisors are valid for a given refclk with
  * the given connectors.
@@ -726,7 +726,7 @@ static int intel_crtc_mode_set(struct drm_crtc *crtc,
         int dspsize_reg = (pipe == 0) ? DSPASIZE : DSPBSIZE;
         int dsppos_reg = (pipe == 0) ? DSPAPOS : DSPBPOS;
         int pipesrc_reg = (pipe == 0) ? PIPEASRC : PIPEBSRC;
-        int refclk;
+        int refclk, num_outputs = 0;
         intel_clock_t clock;
         u32 dpll = 0, fp = 0, dspcntr, pipeconf;
         bool ok, is_sdvo = false, is_dvo = false;
@@ -763,9 +763,14 @@ static int intel_crtc_mode_set(struct drm_crtc *crtc,
                         is_crt = true;
                         break;
                 }
+
+                num_outputs++;
         }
 
-        if (IS_I9XX(dev)) {
+        if (is_lvds && dev_priv->lvds_use_ssc && num_outputs < 2) {
+                refclk = dev_priv->lvds_ssc_freq * 1000;
+                DRM_DEBUG("using SSC reference clock of %d MHz\n", refclk / 1000);
+        } else if (IS_I9XX(dev)) {
                 refclk = 96000;
         } else {
                 refclk = 48000;
@@ -824,11 +829,14 @@ static int intel_crtc_mode_set(struct drm_crtc *crtc,
                 }
         }
 
-        if (is_tv) {
+        if (is_sdvo && is_tv)
+                dpll |= PLL_REF_INPUT_TVCLKINBC;
+        else if (is_tv)
                 /* XXX: just matching BIOS for now */
-/*      dpll |= PLL_REF_INPUT_TVCLKINBC; */
+                /*      dpll |= PLL_REF_INPUT_TVCLKINBC; */
                 dpll |= 3;
-        }
+        else if (is_lvds && dev_priv->lvds_use_ssc && num_outputs < 2)
+                dpll |= PLLB_REF_INPUT_SPREADSPECTRUMIN;
         else
                 dpll |= PLL_REF_INPUT_DREFCLK;