[PATCH 3/3] drm: handle override edid and firmware EDID at drm_do_get_edid() level

[Jani Nikula]

Handle debugfs override edid and firmware edid at the low level to
transparently and completely replace the real edid. Previously, we
practically only used the modes from the override EDID, and none of the
other data. This also prevents actual EDID reads when the EDID is to be
overridden, but retains the DDC probe.

FIXME: validate override edid, deduplicate firmware edid validation.

Signed-off-by: Jani Nikula <jani.nikula at intel.com>
---
 drivers/gpu/drm/drm_edid.c         | 15 +++++++++++++++
 drivers/gpu/drm/drm_probe_helper.c | 19 +------------------
 2 files changed, 16 insertions(+), 18 deletions(-)

diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index 362036360724..054e2d74eafc 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -1309,6 +1309,10 @@ static void connector_bad_edid(struct drm_connector *connector,
  * level, drivers must make all reasonable efforts to expose it as an I2C
  * adapter and use drm_get_edid() instead of abusing this function.
  *
+ * The EDID may be overridden using debugfs override_edid or firmare EDID
+ * (drm_load_edid_firmware()), in this priority order. Having either of them
+ * bypasses actual EDID reads.
+ *
  * Return: Pointer to valid EDID or NULL if we couldn't find any.
  */
 struct edid *drm_do_get_edid(struct drm_connector *connector,
@@ -1318,6 +1322,17 @@ struct edid *drm_do_get_edid(struct drm_connector *connector,
 {
 	int i, j = 0, valid_extensions = 0;
 	u8 *edid, *new;
+	struct edid *override = NULL;
+
+	if (connector->override_edid)
+		override = drm_edid_duplicate((const struct edid *)
+					      connector->edid_blob_ptr->data);
+
+	if (!override)
+		override = drm_load_edid_firmware(connector);
+
+	if (!IS_ERR_OR_NULL(override))
+		return override;
 
 	if ((edid = kmalloc(EDID_LENGTH, GFP_KERNEL)) == NULL)
 		return NULL;
diff --git a/drivers/gpu/drm/drm_probe_helper.c b/drivers/gpu/drm/drm_probe_helper.c
index 358957118ca9..871326cbc465 100644
--- a/drivers/gpu/drm/drm_probe_helper.c
+++ b/drivers/gpu/drm/drm_probe_helper.c
@@ -199,8 +199,6 @@ drm_connector_detect(struct drm_connector *connector, bool force)
  *    drm_mode_probed_add(). New modes start their life with status as OK.
  *    Modes are added from a single source using the following priority order.
  *
- *    - debugfs 'override_edid' (used for testing only)
- *    - firmware EDID (drm_load_edid_firmware())
  *    - &drm_connector_helper_funcs.get_modes vfunc
  *    - if the connector status is connector_status_connected, standard
  *      VESA DMT modes up to 1024x768 are automatically added
@@ -305,22 +303,7 @@ int drm_helper_probe_single_connector_modes(struct drm_connector *connector,
 		goto prune;
 	}
 
-	if (connector->override_edid) {
-		struct edid *edid = (struct edid *) connector->edid_blob_ptr->data;
-
-		count = drm_add_edid_modes(connector, edid);
-		drm_edid_to_eld(connector, edid);
-	} else {
-		struct edid *edid = drm_load_edid_firmware(connector);
-		if (!IS_ERR_OR_NULL(edid)) {
-			drm_mode_connector_update_edid_property(connector, edid);
-			count = drm_add_edid_modes(connector, edid);
-			drm_edid_to_eld(connector, edid);
-			kfree(edid);
-		}
-		if (count == 0)
-			count = (*connector_funcs->get_modes)(connector);
-	}
+	count = (*connector_funcs->get_modes)(connector);
 
 	if (count == 0 && connector->status == connector_status_connected)
 		count = drm_add_modes_noedid(connector, 1024, 768);
-- 
2.1.4