[RFC PATCH 01/11] drm/i915/display: Add new interface for getting dc_state

["Jouni Högander" <jouni.hogander@intel.com>]

To implement workaround for underrun on idle PSR HW issue (Wa_16025596647)
we need to have current configured DC state available. Add new interface
for this purpose.

Signed-off-by: Jouni Högander <jouni.hogander@intel.com>
---
 .../drm/i915/display/intel_display_power.c    | 29 +++++++++++++++++++
 .../drm/i915/display/intel_display_power.h    |  1 +
 2 files changed, 30 insertions(+)

diff --git a/drivers/gpu/drm/i915/display/intel_display_power.c b/drivers/gpu/drm/i915/display/intel_display_power.c
index f7171e6932dc..6dfe85a5528f 100644
--- a/drivers/gpu/drm/i915/display/intel_display_power.c
+++ b/drivers/gpu/drm/i915/display/intel_display_power.c
@@ -322,6 +322,35 @@ void intel_display_power_set_target_dc_state(struct intel_display *display,
 	mutex_unlock(&power_domains->lock);
 }
 
+/**
+ * intel_display_power_get_current_dc_state - Set target dc state.
+ * @display: display device
+ *
+ * This function set the "DC off" power well target_dc_state,
+ * based upon this target_dc_stste, "DC off" power well will
+ * enable desired DC state.
+ */
+u32 intel_display_power_get_current_dc_state(struct intel_display *display)
+{
+	struct i915_power_well *power_well;
+	struct i915_power_domains *power_domains = &display->power.domains;
+	u32 current_dc_state = DC_STATE_DISABLE;
+
+	mutex_lock(&power_domains->lock);
+	power_well = lookup_power_well(display, SKL_DISP_DC_OFF);
+
+	if (drm_WARN_ON(display->drm, !power_well))
+		goto unlock;
+
+	current_dc_state = intel_power_well_is_enabled(display, power_well) ?
+		DC_STATE_DISABLE : power_domains->target_dc_state;
+
+unlock:
+	mutex_unlock(&power_domains->lock);
+
+	return current_dc_state;
+}
+
 static void __async_put_domains_mask(struct i915_power_domains *power_domains,
 				     struct intel_power_domain_mask *mask)
 {
diff --git a/drivers/gpu/drm/i915/display/intel_display_power.h b/drivers/gpu/drm/i915/display/intel_display_power.h
index 1b53d67f9b60..f8813b0e16df 100644
--- a/drivers/gpu/drm/i915/display/intel_display_power.h
+++ b/drivers/gpu/drm/i915/display/intel_display_power.h
@@ -183,6 +183,7 @@ void intel_display_power_suspend(struct intel_display *display);
 void intel_display_power_resume(struct intel_display *display);
 void intel_display_power_set_target_dc_state(struct intel_display *display,
 					     u32 state);
+u32 intel_display_power_get_current_dc_state(struct intel_display *display);
 
 bool intel_display_power_is_enabled(struct intel_display *display,
 				    enum intel_display_power_domain domain);
-- 
2.43.0