[Intel-gfx] [PATCH v2 1/6] drm/i915/runtime_pm: Share code to enable/disable PCH reset handshake

[José Roberto de Souza]

Instead of have the same code spread into 4 platforms lets share it.
BXT do not have a PCH so here also handling this case by unseting
RESET_PCH_HANDSHAKE_ENABLE.

v2(Rodrigo):
- renamed to intel_pch_reset_handshake()
- added comment about why BXT need the bit to be unset

Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
Signed-off-by: José Roberto de Souza <jose.souza at intel.com>
---
 drivers/gpu/drm/i915/intel_runtime_pm.c | 36 ++++++++++++-------------
 1 file changed, 17 insertions(+), 19 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_runtime_pm.c b/drivers/gpu/drm/i915/intel_runtime_pm.c
index 9bebec389de1..1bcd0e51fca1 100644
--- a/drivers/gpu/drm/i915/intel_runtime_pm.c
+++ b/drivers/gpu/drm/i915/intel_runtime_pm.c
@@ -3239,18 +3239,29 @@ static void icl_mbus_init(struct drm_i915_private *dev_priv)
 	I915_WRITE(MBUS_ABOX_CTL, val);
 }
 
+static void intel_pch_reset_handshake(struct drm_i915_private *dev_priv)
+{
+	u32 val = I915_READ(HSW_NDE_RSTWRN_OPT);
+
+	/* BXT don't have PCH and it requires that this bit is always unset */
+	if (HAS_PCH_SPLIT(dev_priv))
+		val |= RESET_PCH_HANDSHAKE_ENABLE;
+	else
+		val &= ~RESET_PCH_HANDSHAKE_ENABLE;
+
+	I915_WRITE(HSW_NDE_RSTWRN_OPT, val);
+}
+
 static void skl_display_core_init(struct drm_i915_private *dev_priv,
 				   bool resume)
 {
 	struct i915_power_domains *power_domains = &dev_priv->power_domains;
 	struct i915_power_well *well;
-	uint32_t val;
 
 	gen9_set_dc_state(dev_priv, DC_STATE_DISABLE);
 
 	/* enable PCH reset handshake */
-	val = I915_READ(HSW_NDE_RSTWRN_OPT);
-	I915_WRITE(HSW_NDE_RSTWRN_OPT, val | RESET_PCH_HANDSHAKE_ENABLE);
+	intel_pch_reset_handshake(dev_priv);
 
 	/* enable PG1 and Misc I/O */
 	mutex_lock(&power_domains->lock);
@@ -3306,19 +3317,10 @@ void bxt_display_core_init(struct drm_i915_private *dev_priv,
 {
 	struct i915_power_domains *power_domains = &dev_priv->power_domains;
 	struct i915_power_well *well;
-	uint32_t val;
 
 	gen9_set_dc_state(dev_priv, DC_STATE_DISABLE);
 
-	/*
-	 * NDE_RSTWRN_OPT RST PCH Handshake En must always be 0b on BXT
-	 * or else the reset will hang because there is no PCH to respond.
-	 * Move the handshake programming to initialization sequence.
-	 * Previously was left up to BIOS.
-	 */
-	val = I915_READ(HSW_NDE_RSTWRN_OPT);
-	val &= ~RESET_PCH_HANDSHAKE_ENABLE;
-	I915_WRITE(HSW_NDE_RSTWRN_OPT, val);
+	intel_pch_reset_handshake(dev_priv);
 
 	/* Enable PG1 */
 	mutex_lock(&power_domains->lock);
@@ -3439,9 +3441,7 @@ static void cnl_display_core_init(struct drm_i915_private *dev_priv, bool resume
 	gen9_set_dc_state(dev_priv, DC_STATE_DISABLE);
 
 	/* 1. Enable PCH Reset Handshake */
-	val = I915_READ(HSW_NDE_RSTWRN_OPT);
-	val |= RESET_PCH_HANDSHAKE_ENABLE;
-	I915_WRITE(HSW_NDE_RSTWRN_OPT, val);
+	intel_pch_reset_handshake(dev_priv);
 
 	/* 2. Enable Comp */
 	val = I915_READ(CHICKEN_MISC_2);
@@ -3524,9 +3524,7 @@ static void icl_display_core_init(struct drm_i915_private *dev_priv,
 	gen9_set_dc_state(dev_priv, DC_STATE_DISABLE);
 
 	/* 1. Enable PCH reset handshake. */
-	val = I915_READ(HSW_NDE_RSTWRN_OPT);
-	val |= RESET_PCH_HANDSHAKE_ENABLE;
-	I915_WRITE(HSW_NDE_RSTWRN_OPT, val);
+	intel_pch_reset_handshake(dev_priv);
 
 	for (port = PORT_A; port <= PORT_B; port++) {
 		/* 2. Enable DDI combo PHY comp. */
-- 
2.19.0