[PATCH v2] drm/dp: Add function to parse EDID descriptors for adaptive sync limits

[Manasi Navare]

Adaptive Sync is a VESA feature so add a DRM core helper to parse
the EDID's detailed descritors to obtain the adaptive sync monitor range.
Store this info as part fo drm_display_info so it can be used
across all drivers.
This part of the code is stripped out of amdgpu's function
amdgpu_dm_update_freesync_caps() to make it generic and be used
across all DRM drivers

v2:
* Change vmin and vmax to use u8 (Ville)
* Dont store pixel clock since that is just a max dotclock
and not related to VRR mode (Manasi)

Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
Cc: Harry Wentland <harry.wentland at amd.com>
Cc: Clinton A Taylor <clinton.a.taylor at intel.com>
Cc: Nicholas Kazlauskas <nicholas.kazluaskas at amd.com>
Signed-off-by: Manasi Navare <manasi.d.navare at intel.com>
---
 drivers/gpu/drm/drm_edid.c  | 51 +++++++++++++++++++++++++++++++++++++
 include/drm/drm_connector.h | 22 ++++++++++++++++
 include/drm/drm_edid.h      |  2 ++
 3 files changed, 75 insertions(+)

diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index 99769d6c9f84..52781a0e708b 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -4880,6 +4880,54 @@ static void drm_parse_cea_ext(struct drm_connector *connector,
 	}
 }
 
+void drm_get_adaptive_sync_limits(struct drm_connector *connector,
+				  const struct edid *edid)
+{
+	struct drm_display_info *info = &connector->display_info;
+	const struct detailed_timing *timing;
+	const struct detailed_non_pixel *data;
+	const struct detailed_data_monitor_range *range;
+	int i;
+
+	/*
+	 * Restrict Adaptive Sync only for dp and edp
+	 */
+	if (connector->connector_type != DRM_MODE_CONNECTOR_DisplayPort &&
+	    connector->connector_type != DRM_MODE_CONNECTOR_eDP)
+		return;
+
+	if (edid->version <= 1 && !(edid->version == 1 && edid->revision > 1))
+		return;
+
+	for (i = 0; i < 4; i++) {
+		timing  = &edid->detailed_timings[i];
+		data    = &timing->data.other_data;
+		range   = &data->data.range;
+		/*
+		 * Check if monitor has continuous frequency mode
+		 */
+		if (data->type != EDID_DETAIL_MONITOR_RANGE)
+			continue;
+		/*
+		 * Check for flag range limits only. If flag == 1 then
+		 * no additional timing information provided.
+		 * Default GTF, GTF Secondary curve and CVT are not
+		 * supported
+		 */
+		if (range->flags != 1)
+			continue;
+
+		info->adaptive_sync.min_vfreq = range->min_vfreq;
+		info->adaptive_sync.max_vfreq = range->max_vfreq;
+
+		DRM_DEBUG_KMS("Adaptive Sync refresh rate range is %d Hz - %d Hz\n",
+			      info->adaptive_sync.min_vfreq,
+			      info->adaptive_sync.max_vfreq);
+		break;
+	}
+}
+EXPORT_SYMBOL(drm_get_adaptive_sync_limits);
+
 /* A connector has no EDID information, so we've got no EDID to compute quirks from. Reset
  * all of the values which would have been set from EDID
  */
@@ -4901,6 +4949,7 @@ drm_reset_display_info(struct drm_connector *connector)
 	memset(&info->hdmi, 0, sizeof(info->hdmi));
 
 	info->non_desktop = 0;
+	memset(&info->adaptive_sync, 0, sizeof(info->adaptive_sync));
 }
 
 u32 drm_add_display_info(struct drm_connector *connector, const struct edid *edid)
@@ -4916,6 +4965,8 @@ u32 drm_add_display_info(struct drm_connector *connector, const struct edid *edi
 
 	info->non_desktop = !!(quirks & EDID_QUIRK_NON_DESKTOP);
 
+	drm_get_adaptive_sync_limits(connector, edid);
+
 	DRM_DEBUG_KMS("non_desktop set to %d\n", info->non_desktop);
 
 	if (edid->revision < 3)
diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
index 221910948b37..77df404a2e01 100644
--- a/include/drm/drm_connector.h
+++ b/include/drm/drm_connector.h
@@ -254,6 +254,23 @@ enum drm_panel_orientation {
 	DRM_MODE_PANEL_ORIENTATION_RIGHT_UP,
 };
 
+/**
+ * struct drm_adaptive_sync_info - Panel's Adaptive Sync capabilities for
+ * &drm_display_info
+ *
+ * This struct is used to store a Panel's Adaptive Sync capabilities
+ * as parsed from EDID's detailed monitor range descriptor block.
+ *
+ * @min_vfreq: This is the min supported refresh rate in Hz from
+ *             EDID's detailed monitor range.
+ * @max_vfreq: This is the max supported refresh rate in Hz from
+ *             EDID's detailed monitor range
+ */
+struct drm_adaptive_sync_info {
+	u8 min_vfreq;
+	u8 max_vfreq;
+};
+
 /*
  * This is a consolidated colorimetry list supported by HDMI and
  * DP protocol standard. The respective connectors will register
@@ -465,6 +482,11 @@ struct drm_display_info {
 	 * @non_desktop: Non desktop display (HMD).
 	 */
 	bool non_desktop;
+
+	/**
+	 * @adaptive_sync: Adaptive Sync capabilities of the DP/eDP sink
+	 */
+	struct drm_adaptive_sync_info adaptive_sync;
 };
 
 int drm_display_info_set_bus_formats(struct drm_display_info *info,
diff --git a/include/drm/drm_edid.h b/include/drm/drm_edid.h
index f0b03d401c27..b9a230aa3e69 100644
--- a/include/drm/drm_edid.h
+++ b/include/drm/drm_edid.h
@@ -503,4 +503,6 @@ void drm_edid_get_monitor_name(struct edid *edid, char *name,
 struct drm_display_mode *drm_mode_find_dmt(struct drm_device *dev,
 					   int hsize, int vsize, int fresh,
 					   bool rb);
+void drm_get_adaptive_sync_limits(struct drm_connector *connector,
+				  const struct edid *edid);
 #endif /* __DRM_EDID_H__ */
-- 
2.19.1