drm/i915: Fix 66 MHz LVDS SSC freq for gen2

Store the SSC refclock frequency in kHz to get more accuracy. Currently
we're pretending that 66 MHz is ~66000 kHz, when in fact it is actually
~66667 kHz. By storing the less rounded kHz value we get a much better
accuracy for out pixel clock calculations.

Cc: Bruno Prémont <bonbons@linux-vserver.org>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Tested-by: Bruno Prémont <bonbons@linux-vserver.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

2 files changed, 10 insertions, 11 deletions

diff --git a/drivers/gpu/drm/i915/intel_bios.c b/drivers/gpu/drm/i915/intel_bios.c
index e4fba39631a5..f88e5079a3f5 100644
--- a/drivers/gpu/drm/i915/intel_bios.c
+++ b/drivers/gpu/drm/i915/intel_bios.c
@@ -327,12 +327,12 @@ static int intel_bios_ssc_frequency(struct drm_device *dev,
 {
 	switch (INTEL_INFO(dev)->gen) {
 	case 2:
-		return alternate ? 66 : 48;
+		return alternate ? 66667 : 48000;
 	case 3:
 	case 4:
-		return alternate ? 100 : 96;
+		return alternate ? 100000 : 96000;
 	default:
-		return alternate ? 100 : 120;
+		return alternate ? 100000 : 120000;
 	}
 }
 
@@ -796,7 +796,7 @@ init_vbt_defaults(struct drm_i915_private *dev_priv)
 	 */
 	dev_priv->vbt.lvds_ssc_freq = intel_bios_ssc_frequency(dev,
 			!HAS_PCH_SPLIT(dev));
-	DRM_DEBUG_KMS("Set default to SSC at %dMHz\n", dev_priv->vbt.lvds_ssc_freq);
+	DRM_DEBUG_KMS("Set default to SSC at %d kHz\n", dev_priv->vbt.lvds_ssc_freq);
 
 	for (port = PORT_A; port < I915_MAX_PORTS; port++) {
 		struct ddi_vbt_port_info *info =
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 14e0b80c5641..9404b50ee8c4 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -4761,9 +4761,8 @@ static int i9xx_get_refclk(struct drm_crtc *crtc, int num_connectors)
 		refclk = 100000;
 	} else if (intel_pipe_has_type(crtc, INTEL_OUTPUT_LVDS) &&
 	    intel_panel_use_ssc(dev_priv) && num_connectors < 2) {
-		refclk = dev_priv->vbt.lvds_ssc_freq * 1000;
-		DRM_DEBUG_KMS("using SSC reference clock of %d MHz\n",
-			      refclk / 1000);
+		refclk = dev_priv->vbt.lvds_ssc_freq;
+		DRM_DEBUG_KMS("using SSC reference clock of %d kHz\n", refclk);
 	} else if (!IS_GEN2(dev)) {
 		refclk = 96000;
 	} else {
@@ -5909,9 +5908,9 @@ static int ironlake_get_refclk(struct drm_crtc *crtc)
 	}
 
 	if (is_lvds && intel_panel_use_ssc(dev_priv) && num_connectors < 2) {
-		DRM_DEBUG_KMS("using SSC reference clock of %d MHz\n",
+		DRM_DEBUG_KMS("using SSC reference clock of %d kHz\n",
 			      dev_priv->vbt.lvds_ssc_freq);
-		return dev_priv->vbt.lvds_ssc_freq * 1000;
+		return dev_priv->vbt.lvds_ssc_freq;
 	}
 
 	return 120000;
@@ -6173,7 +6172,7 @@ static uint32_t ironlake_compute_dpll(struct intel_crtc *intel_crtc,
 	factor = 21;
 	if (is_lvds) {
 		if ((intel_panel_use_ssc(dev_priv) &&
-		     dev_priv->vbt.lvds_ssc_freq == 100) ||
+		     dev_priv->vbt.lvds_ssc_freq == 100000) ||
 		    (HAS_PCH_IBX(dev) && intel_is_dual_link_lvds(dev)))
 			factor = 25;
 	} else if (intel_crtc->config.sdvo_tv_clock)
@@ -7888,7 +7887,7 @@ static int i9xx_pll_refclk(struct drm_device *dev,
 	u32 dpll = pipe_config->dpll_hw_state.dpll;
 
 	if ((dpll & PLL_REF_INPUT_MASK) == PLLB_REF_INPUT_SPREADSPECTRUMIN)
-		return dev_priv->vbt.lvds_ssc_freq * 1000;
+		return dev_priv->vbt.lvds_ssc_freq;
 	else if (HAS_PCH_SPLIT(dev))
 		return 120000;
 	else if (!IS_GEN2(dev))