drm/edid: Add function to parse EDID descriptors for monitor range

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

v6:
* Call it monitor_range (Ville)
v5:
* Use the renamed flags
v4:
* Use is_display_descriptor() (Ville)
* Name the monitor range flags (Ville)
v3:
* Remove the edid parsing restriction for just DP (Nicholas)
* Use drm_for_each_detailed_block (Ville)
* Make the drm_get_adaptive_sync_range function static (Harry, Jani)
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@linux.intel.com>
Cc: Harry Wentland <harry.wentland@amd.com>
Cc: Clinton A Taylor <clinton.a.taylor@intel.com>
Cc: Kazlauskas Nicholas <Nicholas.Kazlauskas@amd.com>
Signed-off-by: Manasi Navare <manasi.d.navare@intel.com>
Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200310231651.13841-2-manasi.d.navare@intel.com

drivers/gpu/drm/drm_edid.c

@@ -4938,6 +4938,47 @@ static void drm_parse_cea_ext(struct drm_connector *connector,
 	}
 }
 
+static
+void get_monitor_range(struct detailed_timing *timing,
+		       void *info_monitor_range)
+{
+	struct drm_monitor_range_info *monitor_range = info_monitor_range;
+	const struct detailed_non_pixel *data = &timing->data.other_data;
+	const struct detailed_data_monitor_range *range = &data->data.range;
+
+	if (!is_display_descriptor((const u8 *)timing, EDID_DETAIL_MONITOR_RANGE))
+		return;
+
+	/*
+	 * 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 != DRM_EDID_RANGE_LIMITS_ONLY_FLAG)
+		return;
+
+	monitor_range->min_vfreq = range->min_vfreq;
+	monitor_range->max_vfreq = range->max_vfreq;
+}
+
+static
+void drm_get_monitor_range(struct drm_connector *connector,
+			   const struct edid *edid)
+{
+	struct drm_display_info *info = &connector->display_info;
+
+	if (!version_greater(edid, 1, 1))
+		return;
+
+	drm_for_each_detailed_block((u8 *)edid, get_monitor_range,
+				    &info->monitor_range);
+
+	DRM_DEBUG_KMS("Supported Monitor Refresh rate range is %d Hz - %d Hz\n",
+		      info->monitor_range.min_vfreq,
+		      info->monitor_range.max_vfreq);
+}
+
 /* 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
  */
@@ -4960,6 +5001,7 @@ drm_reset_display_info(struct drm_connector *connector)
 	memset(&info->hdmi, 0, sizeof(info->hdmi));
 
 	info->non_desktop = 0;
+	memset(&info->monitor_range, 0, sizeof(info->monitor_range));
 }
 
 u32 drm_add_display_info(struct drm_connector *connector, const struct edid *edid)
@@ -4975,6 +5017,8 @@ u32 drm_add_display_info(struct drm_connector *connector, const struct edid *edi
 
 	info->non_desktop = !!(quirks & EDID_QUIRK_NON_DESKTOP);
 
+	drm_get_monitor_range(connector, edid);
+
 	DRM_DEBUG_KMS("non_desktop set to %d\n", info->non_desktop);
 
 	if (edid->revision < 3)

include/drm/drm_connector.h

@@ -254,6 +254,23 @@ enum drm_panel_orientation {
 	DRM_MODE_PANEL_ORIENTATION_RIGHT_UP,
 };
 
+/**
+ * struct drm_monitor_range_info - Panel's Monitor range in EDID for
+ * &drm_display_info
+ *
+ * This struct is used to store a frequency range supported by panel
+ * 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_monitor_range_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
@@ -473,6 +490,11 @@ struct drm_display_info {
 	 * @non_desktop: Non desktop display (HMD).
 	 */
 	bool non_desktop;
+
+	/**
+	 * @monitor_range: Frequency range supported by monitor range descriptor
+	 */
+	struct drm_monitor_range_info monitor_range;
 };
 
 int drm_display_info_set_bus_formats(struct drm_display_info *info,