[PATCH 7/8] drm/i915/skl: Assert the requirements to enter or exit DC6.

[Animesh Manna <animesh.manna@xxxxxxxxx>]

From: Suketu Shah <suketu.j.shah@xxxxxxxxx>

Warn if the conditions to enter or exit DC6 are not satisfied such
as support for runtime PM, state of power well, CSR loading etc.

v2: Removed camelcase in functions and variables.

v3: Do some minimal check to assert if CSR program is not loaded.

v4:
1] Correct the check for backlight-disabling in assert_can_enable_dc6().
2] Check csr.loaded = false before disabling DC6 and simplify other checks.

v5:
1] Remove checks for DC5 state from assert_can_enable_dc6 function as DC5 is no
   longer enabled before enabling DC6.
2] Correct the check for CSR-loading in assert_can_disable_dc6 function as CSR must
   be loaded for context restore to happen on DC6 disabling.

v6:
1] It's okay to explicitly disable DC6 during driver-load/resume even though it might
   already be disabled and so don't warn about it.

v7: Rebase to latest.

v8: Sqashed the patch from Imre -
[PATCH] drm/i915/skl: avoid false CSR fw not loaded WARN during driver load/resume

v9: After adding dmc ver 1.0 support rebased on top of nightly. (Animesh)

Issue: VIZ-2819
Signed-off-by: A.Sunil Kamath <sunil.kamath@xxxxxxxxx>
Signed-off-by: Suketu Shah <suketu.j.shah@xxxxxxxxx>
Signed-off-by: Damien Lespiau <damien.lespiau@xxxxxxxxx>
Signed-off-by: Animesh Manna <animesh.manna@xxxxxxxxx>
---
 drivers/gpu/drm/i915/intel_runtime_pm.c | 38 +++++++++++++++++++++++++++------
 1 file changed, 32 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_runtime_pm.c b/drivers/gpu/drm/i915/intel_runtime_pm.c
index cc94503..9196de3 100644
--- a/drivers/gpu/drm/i915/intel_runtime_pm.c
+++ b/drivers/gpu/drm/i915/intel_runtime_pm.c
@@ -1,5 +1,5 @@
-/*
- * Copyright © 2012-2014 Intel Corporation
+		/*
+ * Cipyright © 2012-2014 Intel Corporation
  *
  * Permission is hereby granted, free of charge, to any person obtaining a
  * copy of this software and associated documentation files (the "Software"),
@@ -408,12 +408,39 @@ static void gen9_disable_dc5(struct drm_i915_private *dev_priv)
 	POSTING_READ(DC_STATE_EN);
 }
 
-static void skl_enable_dc6(struct drm_i915_private *dev_priv)
+static void assert_can_enable_dc6(struct drm_i915_private *dev_priv)
 {
 	struct drm_device *dev = dev_priv->dev;
+
+	WARN(!IS_SKYLAKE(dev), "Platform doesn't support DC6.\n");
+	WARN(!HAS_RUNTIME_PM(dev), "Runtime PM not enabled.\n");
+	WARN(I915_READ(UTIL_PIN_CTL) & UTIL_PIN_ENABLE,
+		"Backlight is not disabled.\n");
+	WARN((I915_READ(DC_STATE_EN) & DC_STATE_EN_UPTO_DC6),
+		"DC6 already programmed to be enabled.\n");
+
+	assert_csr_loaded(dev_priv);
+}
+
+static void assert_can_disable_dc6(struct drm_i915_private *dev_priv)
+{
+	/*
+	 * During initialization, the firmware may not be loaded yet.
+	 * We still want to make sure that the DC enabling flag is cleared.
+	 */
+	if (dev_priv->power_domains.initializing)
+		return;
+
+	assert_csr_loaded(dev_priv);
+	WARN(!(I915_READ(DC_STATE_EN) & DC_STATE_EN_UPTO_DC6),
+		"DC6 already programmed to be disabled.\n");
+}
+
+static void skl_enable_dc6(struct drm_i915_private *dev_priv)
+{
 	uint32_t val;
 
-	WARN_ON(!IS_SKYLAKE(dev));
+	assert_can_enable_dc6(dev_priv);
 
 	DRM_DEBUG_KMS("Enabling DC6\n");
 
@@ -428,10 +455,9 @@ static void skl_enable_dc6(struct drm_i915_private *dev_priv)
 
 static void skl_disable_dc6(struct drm_i915_private *dev_priv)
 {
-	struct drm_device *dev = dev_priv->dev;
 	uint32_t val;
 
-	WARN_ON(!IS_SKYLAKE(dev));
+	assert_can_disable_dc6(dev_priv);
 
 	DRM_DEBUG_KMS("Disabling DC6\n");
 
-- 
2.0.2

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