drm/i915: fix display power sw state reporting

Atm, we refcount both power domains and power wells and
intel_display_power_enabled_sw() returns the power domain refcount. What
the callers are really interested in though is the sw state of the
underlying power wells. Due to this we will report incorrectly that a
given power domain is off if its power wells were enabled via another
power domain, for example POWER_DOMAIN_INIT which enables all power
wells.

As a fix return instead the state based on the refcount of all power
wells included in the passed in power domain.

References: https://bugs.freedesktop.org/show_bug.cgi?id=79505
References: https://bugs.freedesktop.org/show_bug.cgi?id=79038
Reported-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_pm.c

@@ -5572,10 +5572,25 @@ bool intel_display_power_enabled_sw(struct drm_i915_private *dev_priv,
 				    enum intel_display_power_domain domain)
 {
 	struct i915_power_domains *power_domains;
+	struct i915_power_well *power_well;
+	bool is_enabled;
+	int i;
+
+	if (dev_priv->pm.suspended)
+		return false;
 
 	power_domains = &dev_priv->power_domains;
+	is_enabled = true;
+	for_each_power_well_rev(i, power_well, BIT(domain), power_domains) {
+		if (power_well->always_on)
+			continue;
 
-	return power_domains->domain_use_count[domain];
+		if (!power_well->count) {
+			is_enabled = false;
+			break;
+		}
+	}
+	return is_enabled;
 }
 
 bool intel_display_power_enabled(struct drm_i915_private *dev_priv,