drm/i915: add a default always-on power well

So far we distinguished platforms without a dynamic power well with
the HAS_POWER_WELL macro and for such platforms we didn't call any power
domain functions. Instead of doing this check we can add an always-on
power well for these platforms and call the power domain functions
unconditionally. For always-on power wells we only increase/decrease
their refcounts, otherwise they are nop.

This makes high level driver code more readable and as a bonus provides
some idea of the current power domains state for all platforms (once
the relevant debugfs entry is added).

v3: rename intel_power_wells to i9xx_always_on_power_well (Paulo)
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Paulo Zanoni <paulo.zanoni@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_dma.c

@@ -1639,8 +1639,7 @@ int i915_driver_load(struct drm_device *dev, unsigned long flags)
 			goto out_gem_unload;
 	}
 
-	if (HAS_POWER_WELL(dev))
-		intel_power_domains_init(dev);
+	intel_power_domains_init(dev);
 
 	if (drm_core_check_feature(dev, DRIVER_MODESET)) {
 		ret = i915_load_modeset_init(dev);
@@ -1667,8 +1666,7 @@ int i915_driver_load(struct drm_device *dev, unsigned long flags)
 	return 0;
 
 out_power_well:
-	if (HAS_POWER_WELL(dev))
-		intel_power_domains_remove(dev);
+	intel_power_domains_remove(dev);
 	drm_vblank_cleanup(dev);
 out_gem_unload:
 	if (dev_priv->mm.inactive_shrinker.scan_objects)
@@ -1706,13 +1704,11 @@ int i915_driver_unload(struct drm_device *dev)
 
 	intel_gpu_ips_teardown();
 
-	if (HAS_POWER_WELL(dev)) {
-		/* The i915.ko module is still not prepared to be loaded when
-		 * the power well is not enabled, so just enable it in case
-		 * we're going to unload/reload. */
-		intel_display_set_init_power(dev, true);
-		intel_power_domains_remove(dev);
-	}
+	/* The i915.ko module is still not prepared to be loaded when
+	 * the power well is not enabled, so just enable it in case
+	 * we're going to unload/reload. */
+	intel_display_set_init_power(dev, true);
+	intel_power_domains_remove(dev);
 
 	i915_teardown_sysfs(dev);
 

drivers/gpu/drm/i915/i915_drv.h

@@ -1834,7 +1834,6 @@ struct drm_i915_file_private {
 #define HAS_IPS(dev)		(IS_ULT(dev) || IS_BROADWELL(dev))
 
 #define HAS_DDI(dev)		(INTEL_INFO(dev)->has_ddi)
-#define HAS_POWER_WELL(dev)	(IS_HASWELL(dev) || IS_BROADWELL(dev))
 #define HAS_FPGA_DBG_UNCLAIMED(dev)	(INTEL_INFO(dev)->has_fpga_dbg)
 #define HAS_PSR(dev)		(IS_HASWELL(dev) || IS_BROADWELL(dev))
 

drivers/gpu/drm/i915/intel_pm.c

@@ -5644,9 +5644,6 @@ bool intel_display_power_enabled(struct drm_device *dev,
 	bool is_enabled;
 	int i;
 
-	if (!HAS_POWER_WELL(dev))
-		return true;
-
 	power_domains = &dev_priv->power_domains;
 
 	is_enabled = true;
@@ -5754,9 +5751,6 @@ void intel_display_power_get(struct drm_device *dev,
 	struct i915_power_well *power_well;
 	int i;
 
-	if (!HAS_POWER_WELL(dev))
-		return;
-
 	power_domains = &dev_priv->power_domains;
 
 	mutex_lock(&power_domains->lock);
@@ -5773,9 +5767,6 @@ void intel_display_power_put(struct drm_device *dev,
 	struct i915_power_well *power_well;
 	int i;
 
-	if (!HAS_POWER_WELL(dev))
-		return;
-
 	power_domains = &dev_priv->power_domains;
 
 	mutex_lock(&power_domains->lock);
@@ -5814,6 +5805,14 @@ void i915_release_power_well(void)
 }
 EXPORT_SYMBOL_GPL(i915_release_power_well);
 
+static struct i915_power_well i9xx_always_on_power_well[] = {
+	{
+		.name = "always-on",
+		.always_on = 1,
+		.domains = POWER_DOMAIN_MASK,
+	},
+};
+
 static struct i915_power_well hsw_power_wells[] = {
 	{
 		.name = "always-on",
@@ -5852,9 +5851,6 @@ int intel_power_domains_init(struct drm_device *dev)
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct i915_power_domains *power_domains = &dev_priv->power_domains;
 
-	if (!HAS_POWER_WELL(dev))
-		return 0;
-
 	mutex_init(&power_domains->lock);
 
 	/*
@@ -5868,7 +5864,7 @@ int intel_power_domains_init(struct drm_device *dev)
 		set_power_wells(power_domains, bdw_power_wells);
 		hsw_pwr = power_domains;
 	} else {
-		WARN_ON(1);
+		set_power_wells(power_domains, i9xx_always_on_power_well);
 	}
 
 	return 0;
@@ -5886,9 +5882,6 @@ static void intel_power_domains_resume(struct drm_device *dev)
 	struct i915_power_well *power_well;
 	int i;
 
-	if (!HAS_POWER_WELL(dev))
-		return;
-
 	mutex_lock(&power_domains->lock);
 	for_each_power_well(i, power_well, POWER_DOMAIN_MASK, power_domains) {
 		if (power_well->set)
@@ -5907,9 +5900,6 @@ void intel_power_domains_init_hw(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
 
-	if (!HAS_POWER_WELL(dev))
-		return;
-
 	/* For now, we need the power well to be always enabled. */
 	intel_display_set_init_power(dev, true);
 	intel_power_domains_resume(dev);