[PATCH 05/12] drm/i915: Add a function to get the EDID preferred mode for Displayport compliance testing

[Todd Previte <tprevite@gmail.com>]

Add a simple function to pull the preferred mode out of an EDID block. This function
is designed for use during Displayport compliance testing.

Signed-off-by: Todd Previte <tprevite@gmail.com>
---
 drivers/gpu/drm/i915/intel_dp.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index f61502e..6c8f222 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -3351,6 +3351,31 @@ static bool intel_dp_compute_edid_checksum(uint8_t *edid_data, uint8_t *edid_che
 	return edid_ok;
 }
 
+static struct drm_display_mode*
+intel_dp_get_edid_preferred_mode(struct intel_dp *intel_dp)
+{
+	struct drm_display_mode *found_mode = NULL;
+	struct drm_connector *connector = &intel_dp->attached_connector->base;
+	int mode_count = 0;
+
+	list_for_each_entry(found_mode, &connector->probed_modes, head) {
+		/* Check for a preferred mode */
+		if (found_mode->type & DRM_MODE_TYPE_PREFERRED) {
+			/* Found the preferred mode, return it */
+			DRM_DEBUG_KMS("Displayport: Found preferred mode '%s'\n",
+						  found_mode->name);
+			goto exit_with_mode;
+		}
+		mode_count++;
+	}
+	/* No mode found, report the error */
+	DRM_DEBUG_KMS("Displayport: Preferred mode not found in %d probed modes\n",
+				  mode_count);
+
+exit_with_mode:
+	return found_mode;
+}
+
 /* Displayport compliance testing - Link training */
 static uint8_t
 intel_dp_autotest_link_training(struct intel_dp *intel_dp)
-- 
1.9.1