[Intel-gfx] [PATCH 13/13] drm/i915: Implement static DRRS

[Ville Syrjala <ville.syrjala@linux.intel.com>]

From: Ville Syrjälä <ville.syrjala@linux.intel.com>

Let's start supporting static DRRS by trying to match the refresh
rate the user has requested, assuming the panel supports suitable
timings.

For now we stick to just our current two timings:
- fixed_mode: the panel's preferred mode
- downclock_mode: the lowest refresh rate mode we found
Some panels may support more timings than that, but we'll
have to convert our fixed_mode/downclock_mode pointers
into a full list before we can handle that.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
---
 drivers/gpu/drm/i915/display/intel_dp.c    | 11 +++++++++++
 drivers/gpu/drm/i915/display/intel_drrs.c  |  8 +++++---
 drivers/gpu/drm/i915/display/intel_panel.c | 20 ++++++++++++++++++--
 3 files changed, 34 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index af659320c02e..9bd958377a54 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -4599,6 +4599,17 @@ static int intel_dp_get_modes(struct drm_connector *connector)
 			num_modes++;
 		}
 	}
+	if (intel_dp_is_edp(intel_attached_dp(intel_connector)) &&
+	    intel_connector->panel.downclock_mode) {
+		struct drm_display_mode *mode;
+
+		mode = drm_mode_duplicate(connector->dev,
+					  intel_connector->panel.downclock_mode);
+		if (mode) {
+			drm_mode_probed_add(connector, mode);
+			num_modes++;
+		}
+	}
 
 	if (num_modes)
 		return num_modes;
diff --git a/drivers/gpu/drm/i915/display/intel_drrs.c b/drivers/gpu/drm/i915/display/intel_drrs.c
index 5b2eb55c1340..dc1733c9abab 100644
--- a/drivers/gpu/drm/i915/display/intel_drrs.c
+++ b/drivers/gpu/drm/i915/display/intel_drrs.c
@@ -383,7 +383,7 @@ intel_drrs_init(struct intel_connector *connector,
 		return NULL;
 	}
 
-	if (dev_priv->vbt.drrs_type != DRRS_TYPE_SEAMLESS) {
+	if (dev_priv->vbt.drrs_type == DRRS_TYPE_NONE) {
 		drm_dbg_kms(&dev_priv->drm,
 			    "[CONNECTOR:%d:%s] DRRS not supported according to VBT\n",
 			    connector->base.base.id, connector->base.name);
@@ -399,8 +399,10 @@ intel_drrs_init(struct intel_connector *connector,
 	}
 
 	drm_dbg_kms(&dev_priv->drm,
-		    "[CONNECTOR:%d:%s] seamless DRRS supported\n",
-		    connector->base.base.id, connector->base.name);
+		    "[CONNECTOR:%d:%s] %s DRRS supported\n",
+		    connector->base.base.id, connector->base.name,
+		    dev_priv->vbt.drrs_type == DRRS_TYPE_SEAMLESS ?
+		    "seamless" : "static");
 
 	return downclock_mode;
 }
diff --git a/drivers/gpu/drm/i915/display/intel_panel.c b/drivers/gpu/drm/i915/display/intel_panel.c
index 127ad9643360..6ddbb69dcfdc 100644
--- a/drivers/gpu/drm/i915/display/intel_panel.c
+++ b/drivers/gpu/drm/i915/display/intel_panel.c
@@ -49,14 +49,30 @@ const struct drm_display_mode *
 intel_panel_fixed_mode(struct intel_connector *connector,
 		       const struct drm_display_mode *mode)
 {
-	return connector->panel.fixed_mode;
+	const struct drm_display_mode *fixed_mode = connector->panel.fixed_mode;
+	const struct drm_display_mode *downclock_mode = connector->panel.downclock_mode;
+
+	/* pick the one that is closer in terms of vrefresh */
+	/* FIXME make this a a list of modes so we can have more than two */
+	if (fixed_mode && downclock_mode &&
+	    abs(drm_mode_vrefresh(downclock_mode) - drm_mode_vrefresh(mode)) <
+	    abs(drm_mode_vrefresh(fixed_mode) - drm_mode_vrefresh(mode)))
+		return downclock_mode;
+	else
+		return fixed_mode;
 }
 
 const struct drm_display_mode *
 intel_panel_downclock_mode(struct intel_connector *connector,
 			   const struct drm_display_mode *fixed_mode)
 {
-	return connector->panel.downclock_mode;
+	const struct drm_display_mode *downclock_mode = connector->panel.downclock_mode;
+
+	if (downclock_mode &&
+	    drm_mode_vrefresh(downclock_mode) < drm_mode_vrefresh(fixed_mode))
+		return downclock_mode;
+	else
+		return NULL;
 }
 
 int intel_panel_compute_config(struct intel_connector *connector,
-- 
2.34.1