drm/i915: Fix PCH reference clock for FDI on HSW/BDW

The change to skip the PCH reference initialization during fastboot
did end up breaking FDI. To fix that let's try to do the PCH reference
init whenever we're disabling a DPLL that was using said reference
previously.

Cc: stable@vger.kernel.org
Tested-by: Andrija <akijo97@gmail.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=112084
Fixes: b16c7ed95caf ("drm/i915: Do not touch the PCH SSC reference if a PLL is using it")
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191022185643.1483-1-ville.syrjala@linux.intel.com
Reviewed-by: Imre Deak <imre.deak@intel.com>

diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
index 6dc3c93..cbf9cf3 100644 (file)
--- a/drivers/gpu/drm/i915/display/intel_display.c
+++ b/drivers/gpu/drm/i915/display/intel_display.c
@@ -9432,7 +9432,6 @@ static bool wrpll_uses_pch_ssc(struct drm_i915_private *dev_priv,
 static void lpt_init_pch_refclk(struct drm_i915_private *dev_priv)
 {
        struct intel_encoder *encoder;
-       bool pch_ssc_in_use = false;
        bool has_fdi = false;
 
        for_each_intel_encoder(&dev_priv->drm, encoder) {
@@ -9460,22 +9459,24 @@ static void lpt_init_pch_refclk(struct drm_i915_private *dev_priv)
         * clock hierarchy. That would also allow us to do
         * clock bending finally.
         */
+       dev_priv->pch_ssc_use = 0;
+
        if (spll_uses_pch_ssc(dev_priv)) {
                DRM_DEBUG_KMS("SPLL using PCH SSC\n");
-               pch_ssc_in_use = true;
+               dev_priv->pch_ssc_use |= BIT(DPLL_ID_SPLL);
        }
 
        if (wrpll_uses_pch_ssc(dev_priv, DPLL_ID_WRPLL1)) {
                DRM_DEBUG_KMS("WRPLL1 using PCH SSC\n");
-               pch_ssc_in_use = true;
+               dev_priv->pch_ssc_use |= BIT(DPLL_ID_WRPLL1);
        }
 
        if (wrpll_uses_pch_ssc(dev_priv, DPLL_ID_WRPLL2)) {
                DRM_DEBUG_KMS("WRPLL2 using PCH SSC\n");
-               pch_ssc_in_use = true;
+               dev_priv->pch_ssc_use |= BIT(DPLL_ID_WRPLL2);
        }
 
-       if (pch_ssc_in_use)
+       if (dev_priv->pch_ssc_use)
                return;
 
        if (has_fdi) {

diff --git a/drivers/gpu/drm/i915/display/intel_dpll_mgr.c b/drivers/gpu/drm/i915/display/intel_dpll_mgr.c
index ec10fa7..3ce0a02 100644 (file)
--- a/drivers/gpu/drm/i915/display/intel_dpll_mgr.c
+++ b/drivers/gpu/drm/i915/display/intel_dpll_mgr.c
@@ -526,16 +526,31 @@ static void hsw_ddi_wrpll_disable(struct drm_i915_private *dev_priv,
        val = I915_READ(WRPLL_CTL(id));
        I915_WRITE(WRPLL_CTL(id), val & ~WRPLL_PLL_ENABLE);
        POSTING_READ(WRPLL_CTL(id));
+
+       /*
+        * Try to set up the PCH reference clock once all DPLLs
+        * that depend on it have been shut down.
+        */
+       if (dev_priv->pch_ssc_use & BIT(id))
+               intel_init_pch_refclk(dev_priv);
 }
 
 static void hsw_ddi_spll_disable(struct drm_i915_private *dev_priv,
                                 struct intel_shared_dpll *pll)
 {
+       enum intel_dpll_id id = pll->info->id;
        u32 val;
 
        val = I915_READ(SPLL_CTL);
        I915_WRITE(SPLL_CTL, val & ~SPLL_PLL_ENABLE);
        POSTING_READ(SPLL_CTL);
+
+       /*
+        * Try to set up the PCH reference clock once all DPLLs
+        * that depend on it have been shut down.
+        */
+       if (dev_priv->pch_ssc_use & BIT(id))
+               intel_init_pch_refclk(dev_priv);
 }
 
 static bool hsw_ddi_wrpll_get_hw_state(struct drm_i915_private *dev_priv,

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 16e58a7..8622b45 100644 (file)
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1353,6 +1353,8 @@ struct drm_i915_private {
                } contexts;
        } gem;
 
+       u8 pch_ssc_use;
+
        /* For i915gm/i945gm vblank irq workaround */
        u8 vblank_enabled;