drm/i915: Apply the PPS register unlock workaround more consistently

Atm, we apply this workaround somewhat inconsistently at the following
points: driver loading, LVDS init, eDP PPS init, system resume. As this
workaround also affects registers other than PPS (timing, PLL) a more
consistent way is to apply it early after the PPS HW context is known to
be lost: driver loading, system resume and on VLV/CHV/BXT when turning
on power domains.

This is needed by the next patch that removes saving/restoring of the
PP_CONTROL register.

This also removes the incorrect programming of the workaround on HSW+
PCH platforms which don't have the register locking mechanism.

v2: (Ville)
- Don't apply the workaround on BXT.
- Simplify platform checks using HAS_DDI().
v3:
- Move the call of intel_pps_unlock_regs_wa() to the more
  logical vlv_display_power_well_init() (also fixing CHV) (Ville).
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1470827254-21954-5-git-send-email-imre.deak@intel.com

drivers/gpu/drm/i915/i915_drv.c

@@ -1560,6 +1560,7 @@ static int i915_drm_resume(struct drm_device *dev)
 	i915_gem_resume(dev);
 
 	i915_restore_state(dev);
+	intel_pps_unlock_regs_wa(dev_priv);
 	intel_opregion_setup(dev_priv);
 
 	intel_init_pch_refclk(dev);

drivers/gpu/drm/i915/intel_display.c

@@ -14729,6 +14729,30 @@ static bool intel_crt_present(struct drm_device *dev)
 	return true;
 }
 
+void intel_pps_unlock_regs_wa(struct drm_i915_private *dev_priv)
+{
+	int pps_num;
+	int pps_idx;
+
+	if (HAS_DDI(dev_priv))
+		return;
+	/*
+	 * This w/a is needed at least on CPT/PPT, but to be sure apply it
+	 * everywhere where registers can be write protected.
+	 */
+	if (IS_VALLEYVIEW(dev_priv) || IS_CHERRYVIEW(dev_priv))
+		pps_num = 2;
+	else
+		pps_num = 1;
+
+	for (pps_idx = 0; pps_idx < pps_num; pps_idx++) {
+		u32 val = I915_READ(PP_CONTROL(pps_idx));
+
+		val = (val & ~PANEL_UNLOCK_MASK) | PANEL_UNLOCK_REGS;
+		I915_WRITE(PP_CONTROL(pps_idx), val);
+	}
+}
+
 static void intel_pps_init(struct drm_i915_private *dev_priv)
 {
 	if (HAS_PCH_SPLIT(dev_priv) || IS_BROXTON(dev_priv))
@@ -14737,6 +14761,8 @@ static void intel_pps_init(struct drm_i915_private *dev_priv)
 		dev_priv->pps_mmio_base = VLV_PPS_BASE;
 	else
 		dev_priv->pps_mmio_base = PPS_BASE;
+
+	intel_pps_unlock_regs_wa(dev_priv);
 }
 
 static void intel_setup_outputs(struct drm_device *dev)

drivers/gpu/drm/i915/intel_dp.c

@@ -1829,7 +1829,8 @@ static  u32 ironlake_get_pp_control(struct intel_dp *intel_dp)
 	lockdep_assert_held(&dev_priv->pps_mutex);
 
 	control = I915_READ(_pp_ctrl_reg(intel_dp));
-	if (!IS_BROXTON(dev)) {
+	if (WARN_ON(!HAS_DDI(dev_priv) &&
+		    (control & PANEL_UNLOCK_MASK) != PANEL_UNLOCK_REGS)) {
 		control &= ~PANEL_UNLOCK_MASK;
 		control |= PANEL_UNLOCK_REGS;
 	}

drivers/gpu/drm/i915/intel_drv.h

@@ -1162,6 +1162,7 @@ void intel_mark_busy(struct drm_i915_private *dev_priv);
 void intel_mark_idle(struct drm_i915_private *dev_priv);
 void intel_crtc_restore_mode(struct drm_crtc *crtc);
 int intel_display_suspend(struct drm_device *dev);
+void intel_pps_unlock_regs_wa(struct drm_i915_private *dev_priv);
 void intel_encoder_destroy(struct drm_encoder *encoder);
 int intel_connector_init(struct intel_connector *);
 struct intel_connector *intel_connector_alloc(void);

drivers/gpu/drm/i915/intel_lvds.c

@@ -978,14 +978,6 @@ void intel_lvds_init(struct drm_device *dev)
 	int pipe;
 	u8 pin;
 
-	/*
-	 * Unlock registers and just leave them unlocked. Do this before
-	 * checking quirk lists to avoid bogus WARNINGs.
-	 */
-	if (HAS_PCH_SPLIT(dev_priv) || INTEL_GEN(dev_priv) <= 4)
-		I915_WRITE(PP_CONTROL(0),
-			   I915_READ(PP_CONTROL(0)) | PANEL_UNLOCK_REGS);
-
 	if (!intel_lvds_supported(dev))
 		return;
 

drivers/gpu/drm/i915/intel_runtime_pm.c

@@ -592,6 +592,8 @@ void bxt_disable_dc9(struct drm_i915_private *dev_priv)
 	DRM_DEBUG_KMS("Disabling DC9\n");
 
 	gen9_set_dc_state(dev_priv, DC_STATE_DISABLE);
+
+	intel_pps_unlock_regs_wa(dev_priv);
 }
 
 static void assert_csr_loaded(struct drm_i915_private *dev_priv)
@@ -1121,6 +1123,8 @@ static void vlv_display_power_well_init(struct drm_i915_private *dev_priv)
 	}
 
 	i915_redisable_vga_power_on(&dev_priv->drm);
+
+	intel_pps_unlock_regs_wa(dev_priv);
 }
 
 static void vlv_display_power_well_deinit(struct drm_i915_private *dev_priv)