drm/i915/display/vrr: Create VRR file and add VRR capability check

We create a new file for all VRR related helpers.
Also add a function to check vrr capability based on
platform support, DPCD bits and EDID monitor range.

v2:
* Remove author (Jani N)
* Define HAS_VRR (Jani N)
* Ensure intel_dp can be obtained from conn (Jani N)

v3:
* Fix the header indent (Manasi)

Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Manasi Navare <manasi.d.navare@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210125200818.2015-1-manasi.d.navare@intel.com

drivers/gpu/drm/i915/Makefile

@@ -260,6 +260,7 @@ i915-y += \
 	display/intel_sdvo.o \
 	display/intel_tv.o \
 	display/intel_vdsc.o \
+	display/intel_vrr.o \
 	display/vlv_dsi.o \
 	display/vlv_dsi_pll.o
 

drivers/gpu/drm/i915/display/intel_vrr.c

+// SPDX-License-Identifier: MIT
+/*
+ * Copyright © 2020 Intel Corporation
+ *
+ */
+
+#include "i915_drv.h"
+#include "intel_display_types.h"
+#include "intel_vrr.h"
+
+bool intel_vrr_is_capable(struct drm_connector *connector)
+{
+	struct intel_dp *intel_dp;
+	const struct drm_display_info *info = &connector->display_info;
+	struct drm_i915_private *i915 = to_i915(connector->dev);
+
+	if (connector->connector_type != DRM_MODE_CONNECTOR_eDP &&
+	    connector->connector_type != DRM_MODE_CONNECTOR_DisplayPort)
+		return false;
+
+	intel_dp = intel_attached_dp(to_intel_connector(connector));
+	/*
+	 * DP Sink is capable of Variable refresh video timings if
+	 * Ignore MSA bit is set in DPCD.
+	 * EDID monitor range also should be atleast 10 for reasonable
+	 * Adaptive sync/ VRR end user experience.
+	 */
+	return HAS_VRR(i915) &&
+		drm_dp_sink_can_do_video_without_timing_msa(intel_dp->dpcd) &&
+		info->monitor_range.max_vfreq - info->monitor_range.min_vfreq > 10;
+}

drivers/gpu/drm/i915/display/intel_vrr.h

+/* SPDX-License-Identifier: MIT */
+/*
+ * Copyright © 2019 Intel Corporation
+ */
+
+#ifndef __INTEL_VRR_H__
+#define __INTEL_VRR_H__
+
+#include <linux/types.h>
+
+struct drm_connector;
+
+bool intel_vrr_is_capable(struct drm_connector *connector);
+
+#endif /* __INTEL_VRR_H__ */

drivers/gpu/drm/i915/i915_drv.h

@@ -1758,6 +1758,8 @@ tgl_revids_get(struct drm_i915_private *dev_priv)
 
 #define HAS_DISPLAY(dev_priv) (INTEL_INFO(dev_priv)->pipe_mask != 0)
 
+#define HAS_VRR(i915)	(INTEL_GEN(i915) >= 12)
+
 /* Only valid when HAS_DISPLAY() is true */
 #define INTEL_DISPLAY_ENABLED(dev_priv) \
 	(drm_WARN_ON(&(dev_priv)->drm, !HAS_DISPLAY(dev_priv)), !(dev_priv)->params.disable_display)