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

1 files changed, 26 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index dc0d1b61dae4..c0509061f321 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/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)