[PATCH] drm/edid: Handle EDID 1.4 range descriptor h/vfreq offsets

[Ville Syrjala]

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

EDID 1.4 introduced some extra flags in the range
descriptor to support min/max h/vfreq >= 255. Consult them
to correctly parse the vfreq limits.

Cc: stable at vger.kernel.org
Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/6519
Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
---
 drivers/gpu/drm/drm_edid.c | 24 ++++++++++++++++++------
 include/drm/drm_edid.h     |  5 +++++
 2 files changed, 23 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index 90a5e26eafa8..4005dab6147d 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -6020,12 +6020,14 @@ static void drm_parse_cea_ext(struct drm_connector *connector,
 }
 
 static
-void get_monitor_range(const struct detailed_timing *timing,
-		       void *info_monitor_range)
+void get_monitor_range(const struct detailed_timing *timing, void *c)
 {
-	struct drm_monitor_range_info *monitor_range = info_monitor_range;
+	struct detailed_mode_closure *closure = c;
+	struct drm_display_info *info = &closure->connector->display_info;
+	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;
+	const struct edid *edid = closure->drm_edid->edid;
 
 	if (!is_display_descriptor(timing, EDID_DETAIL_MONITOR_RANGE))
 		return;
@@ -6041,18 +6043,28 @@ void get_monitor_range(const struct detailed_timing *timing,
 
 	monitor_range->min_vfreq = range->min_vfreq;
 	monitor_range->max_vfreq = range->max_vfreq;
+
+	if (edid->revision >= 4) {
+		if (data->pad2 & DRM_EDID_RANGE_OFFSET_MIN_VFREQ)
+			monitor_range->min_vfreq += 255;
+		if (data->pad2 & DRM_EDID_RANGE_OFFSET_MAX_VFREQ)
+			monitor_range->max_vfreq += 255;
+	}
 }
 
 static void drm_get_monitor_range(struct drm_connector *connector,
 				  const struct drm_edid *drm_edid)
 {
-	struct drm_display_info *info = &connector->display_info;
+	const struct drm_display_info *info = &connector->display_info;
+	struct detailed_mode_closure closure = {
+		.connector = connector,
+		.drm_edid = drm_edid,
+	};
 
 	if (!version_greater(drm_edid, 1, 1))
 		return;
 
-	drm_for_each_detailed_block(drm_edid, get_monitor_range,
-				    &info->monitor_range);
+	drm_for_each_detailed_block(drm_edid, get_monitor_range, &closure);
 
 	DRM_DEBUG_KMS("Supported Monitor Refresh rate range is %d Hz - %d Hz\n",
 		      info->monitor_range.min_vfreq,
diff --git a/include/drm/drm_edid.h b/include/drm/drm_edid.h
index 2181977ae683..d81da97cad6e 100644
--- a/include/drm/drm_edid.h
+++ b/include/drm/drm_edid.h
@@ -92,6 +92,11 @@ struct detailed_data_string {
 	u8 str[13];
 } __attribute__((packed));
 
+#define DRM_EDID_RANGE_OFFSET_MIN_VFREQ (1 << 0)
+#define DRM_EDID_RANGE_OFFSET_MAX_VFREQ (1 << 1)
+#define DRM_EDID_RANGE_OFFSET_MIN_HFREQ (1 << 2)
+#define DRM_EDID_RANGE_OFFSET_MAX_HFREQ (1 << 3)
+
 #define DRM_EDID_DEFAULT_GTF_SUPPORT_FLAG   0x00
 #define DRM_EDID_RANGE_LIMITS_ONLY_FLAG     0x01
 #define DRM_EDID_SECONDARY_GTF_SUPPORT_FLAG 0x02
-- 
2.35.1