drm/i915: add a debugfs entry for power domain info

Add a debugfs entry showing the use-count for all power domains of each
power well.

v3: address comments from Paulo:
- simplify power_domain_str() by using a switch table
- move power_well::domain_count to power_domains
- WARN_ON decrementing a 0 refcount

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_debugfs.c

@@ -1844,6 +1844,76 @@ static int i915_pc8_status(struct seq_file *m, void *unused)
 	return 0;
 }
 
+static const char *power_domain_str(enum intel_display_power_domain domain)
+{
+	switch (domain) {
+	case POWER_DOMAIN_PIPE_A:
+		return "PIPE_A";
+	case POWER_DOMAIN_PIPE_B:
+		return "PIPE_B";
+	case POWER_DOMAIN_PIPE_C:
+		return "PIPE_C";
+	case POWER_DOMAIN_PIPE_A_PANEL_FITTER:
+		return "PIPE_A_PANEL_FITTER";
+	case POWER_DOMAIN_PIPE_B_PANEL_FITTER:
+		return "PIPE_B_PANEL_FITTER";
+	case POWER_DOMAIN_PIPE_C_PANEL_FITTER:
+		return "PIPE_C_PANEL_FITTER";
+	case POWER_DOMAIN_TRANSCODER_A:
+		return "TRANSCODER_A";
+	case POWER_DOMAIN_TRANSCODER_B:
+		return "TRANSCODER_B";
+	case POWER_DOMAIN_TRANSCODER_C:
+		return "TRANSCODER_C";
+	case POWER_DOMAIN_TRANSCODER_EDP:
+		return "TRANSCODER_EDP";
+	case POWER_DOMAIN_VGA:
+		return "VGA";
+	case POWER_DOMAIN_AUDIO:
+		return "AUDIO";
+	case POWER_DOMAIN_INIT:
+		return "INIT";
+	default:
+		WARN_ON(1);
+		return "?";
+	}
+}
+
+static int i915_power_domain_info(struct seq_file *m, void *unused)
+{
+	struct drm_info_node *node = (struct drm_info_node *) m->private;
+	struct drm_device *dev = node->minor->dev;
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	struct i915_power_domains *power_domains = &dev_priv->power_domains;
+	int i;
+
+	mutex_lock(&power_domains->lock);
+
+	seq_printf(m, "%-25s %s\n", "Power well/domain", "Use count");
+	for (i = 0; i < power_domains->power_well_count; i++) {
+		struct i915_power_well *power_well;
+		enum intel_display_power_domain power_domain;
+
+		power_well = &power_domains->power_wells[i];
+		seq_printf(m, "%-25s %d\n", power_well->name,
+			   power_well->count);
+
+		for (power_domain = 0; power_domain < POWER_DOMAIN_NUM;
+		     power_domain++) {
+			if (!(BIT(power_domain) & power_well->domains))
+				continue;
+
+			seq_printf(m, "  %-23s %d\n",
+				 power_domain_str(power_domain),
+				 power_domains->domain_use_count[power_domain]);
+		}
+	}
+
+	mutex_unlock(&power_domains->lock);
+
+	return 0;
+}
+
 struct pipe_crc_info {
 	const char *name;
 	struct drm_device *dev;
@@ -3079,6 +3149,7 @@ static const struct drm_info_list i915_debugfs_list[] = {
 	{"i915_edp_psr_status", i915_edp_psr_status, 0},
 	{"i915_energy_uJ", i915_energy_uJ, 0},
 	{"i915_pc8_status", i915_pc8_status, 0},
+	{"i915_power_domain_info", i915_power_domain_info, 0},
 };
 #define I915_DEBUGFS_ENTRIES ARRAY_SIZE(i915_debugfs_list)
 

drivers/gpu/drm/i915/i915_drv.h

@@ -971,6 +971,9 @@ struct i915_power_domains {
 	int power_well_count;
 
 	struct mutex lock;
+#if IS_ENABLED(CONFIG_DEBUG_FS)
+	int domain_use_count[POWER_DOMAIN_NUM];
+#endif
 	struct i915_power_well *power_wells;
 };
 

drivers/gpu/drm/i915/intel_pm.c

@@ -5754,8 +5754,13 @@ void intel_display_power_get(struct drm_device *dev,
 	power_domains = &dev_priv->power_domains;
 
 	mutex_lock(&power_domains->lock);
+
+#if IS_ENABLED(CONFIG_DEBUG_FS)
+	power_domains->domain_use_count[domain]++;
+#endif
 	for_each_power_well(i, power_well, BIT(domain), power_domains)
 		__intel_power_well_get(dev, power_well);
+
 	mutex_unlock(&power_domains->lock);
 }
 
@@ -5770,8 +5775,15 @@ void intel_display_power_put(struct drm_device *dev,
 	power_domains = &dev_priv->power_domains;
 
 	mutex_lock(&power_domains->lock);
+
 	for_each_power_well_rev(i, power_well, BIT(domain), power_domains)
 		__intel_power_well_put(dev, power_well);
+
+#if IS_ENABLED(CONFIG_DEBUG_FS)
+	WARN_ON(!power_domains->domain_use_count[domain]);
+	power_domains->domain_use_count[domain]--;
+#endif
+
 	mutex_unlock(&power_domains->lock);
 }