[Intel-gfx] [PATCH 2/5] drm/i915: Parse EDID probed modes for DRRS support

[Vandana Kannan]

From: Pradeep Bhat <pradeep.bhat at intel.com>

This patch and finds out the lowest refresh rate supported for the resolution
same as the fixed_mode, based on the implementaion find_panel_downclock.
It also checks the VBT fields to see if panel supports seamless DRRS or not.
Based on above data it marks whether eDP panel supports seamless DRRS or not.
This information is needed for supporting seamless DRRS switch for
certain power saving usecases. This patch is tested by enabling the DRM logs
and user should see whether Seamless DRRS is supported or not.

Signed-off-by: Pradeep Bhat <pradeep.bhat at intel.com>
Signed-off-by: Vandana Kannan <vandana.kannan at intel.com>
---
 drivers/gpu/drm/i915/i915_drv.h  |    2 ++
 drivers/gpu/drm/i915/intel_dp.c  |   47 ++++++++++++++++++++++++++++++++++++++
 drivers/gpu/drm/i915/intel_drv.h |   29 +++++++++++++++++++++++
 3 files changed, 78 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 02e11dc..c9bca16 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1462,8 +1462,10 @@ typedef struct drm_i915_private {
 	/* Reclocking support */
 	bool render_reclock_avail;
 	bool lvds_downclock_avail;
+	bool edp_downclock_avail;
 	/* indicates the reduced downclock for LVDS*/
 	int lvds_downclock;
+	int edp_downclock;
 	u16 orig_clock;
 
 	bool mchbar_need_disable;
diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 82de200..935b46e 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -3524,6 +3524,48 @@ intel_dp_init_panel_power_sequencer_registers(struct drm_device *dev,
 		      I915_READ(pp_div_reg));
 }
 
+static void
+intel_dp_drrs_initialize(struct intel_digital_port *intel_dig_port,
+			struct intel_connector *intel_connector,
+			struct drm_display_mode *fixed_mode)
+{
+	struct drm_connector *connector = &intel_connector->base;
+	struct intel_dp *intel_dp = &intel_dig_port->dp;
+	struct drm_device *dev = intel_dig_port->base.base.dev;
+	struct drm_i915_private *dev_priv = dev->dev_private;
+
+	/**
+	 * Check if PSR is supported by panel and enabled
+	 * if so then DRRS is reported as not supported for Haswell.
+	 */
+	if (INTEL_INFO(dev)->gen < 8 &&	intel_edp_is_psr_enabled(dev)) {
+		DRM_INFO("eDP panel has PSR enabled. Cannot support DRRS\n");
+		return;
+	}
+
+	/* First check if DRRS is enabled from VBT struct */
+	if (!dev_priv->vbt.intel_drrs_enabled) {
+		DRM_INFO("VBT doesn't support DRRS\n");
+		return;
+	}
+
+	intel_connector->panel.downclock_mode =	intel_find_panel_downclock(dev,
+					fixed_mode, connector);
+
+	if (intel_connector->panel.downclock_mode != NULL &&
+		dev_priv->vbt.drrs_mode == SEAMLESS_DRRS_SUPPORT) {
+		dev_priv->edp_downclock_avail = true;
+		dev_priv->edp_downclock =
+			intel_connector->panel.downclock_mode->clock;
+
+		intel_dp->drrs_state.is_drrs_supported
+				= dev_priv->vbt.drrs_mode;
+
+		intel_dp->drrs_state.drrs_refresh_rate_type = DRRS_HIGH_RR;
+		DRM_INFO("SEAMLESS DRRS supported for eDP panel.\n");
+	}
+}
+
 static bool intel_edp_init_connector(struct intel_dp *intel_dp,
 				     struct intel_connector *intel_connector)
 {
@@ -3537,6 +3579,8 @@ static bool intel_edp_init_connector(struct intel_dp *intel_dp,
 	struct drm_display_mode *scan;
 	struct edid *edid;
 
+	intel_dp->drrs_state.is_drrs_supported = DRRS_NOT_SUPPORTED;
+
 	if (!is_edp(intel_dp))
 		return true;
 
@@ -3581,6 +3625,9 @@ static bool intel_edp_init_connector(struct intel_dp *intel_dp,
 	list_for_each_entry(scan, &connector->probed_modes, head) {
 		if ((scan->type & DRM_MODE_TYPE_PREFERRED)) {
 			fixed_mode = drm_mode_duplicate(dev, scan);
+			if (INTEL_INFO(dev)->gen >= 5)
+				intel_dp_drrs_initialize(intel_dig_port,
+					intel_connector, fixed_mode);
 			break;
 		}
 	}
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 9f8b465..6ec5f4e 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -462,6 +462,34 @@ struct intel_hdmi {
 
 #define DP_MAX_DOWNSTREAM_PORTS		0x10
 
+/**
+ * This enum is used to indicate the DRRS support type.
+ * The values of the enum map 1-to-1 with the values from VBT.
+ */
+enum edp_panel_type {
+	DRRS_NOT_SUPPORTED = -1,
+	STATIC_DRRS_SUPPORT = 0,
+	SEAMLESS_DRRS_SUPPORT = 2
+};
+/**
+ * HIGH_RR is the highest eDP panel refresh rate read from EDID
+ * LOW_RR is the lowest eDP panel refresh rate found from EDID
+ * parsing for same resolution.
+ */
+enum edp_drrs_refresh_rate_type {
+	DRRS_HIGH_RR,
+	DRRS_LOW_RR,
+	DRRS_MAX_RR, /* RR count */
+};
+/**
+ * The drrs_info struct will represent the DRRS feature for eDP
+ * panel.
+ */
+struct drrs_info {
+	int is_drrs_supported;
+	int drrs_refresh_rate_type;
+};
+
 struct intel_dp {
 	uint32_t output_reg;
 	uint32_t aux_ch_ctl_reg;
@@ -487,6 +515,7 @@ struct intel_dp {
 	bool want_panel_vdd;
 	bool psr_setup_done;
 	struct intel_connector *attached_connector;
+	struct drrs_info drrs_state;
 };
 
 struct intel_digital_port {
-- 
1.7.9.5