drm/edid: detach debugfs EDID override from EDID property update

Having the EDID override debugfs directly update the EDID property is
problematic. The update is partial only. The driver has no way of
knowing it's been updated. Mode list is not updated. It's an
inconsistent state.

Detach debugfs EDID override from the property update completely. Only
set and reset a separate override EDID copy from debugfs, and have it
take effect only at detect (via EDID read). The copy is at
connector->edid_override, protected by connector->edid_override_mutex.

This also brings override EDID closer to firmware EDID in behaviour.

Add validation of the override EDID which we completely lacked.

Note that IGT already forces a detect whenever tests update the override
EDID.

v2: Add locking (Ville)

Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/4c875f8e06c4499f498fcf876e1233cbb155ec8a.1666614699.git.jani.nikula@intel.com

1 files changed, 12 insertions, 4 deletions

diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
index b1b2df48d42c..e641a4725f99 100644
--- a/include/drm/drm_connector.h
+++ b/include/drm/drm_connector.h
@@ -1550,12 +1550,20 @@ struct drm_connector {
 	struct drm_cmdline_mode cmdline_mode;
 	/** @force: a DRM_FORCE_<foo> state for forced mode sets */
 	enum drm_connector_force force;
+
+	/**
+	 * @edid_override: Override EDID set via debugfs.
+	 *
+	 * Do not modify or access outside of the drm_edid_override_* family of
+	 * functions.
+	 */
+	const struct drm_edid *edid_override;
+
 	/**
-	 * @override_edid: has the EDID been overwritten through debugfs for
-	 * testing? Do not modify outside of drm_edid_override_set() and
-	 * drm_edid_override_reset().
+	 * @edid_override_mutex: Protect access to edid_override.
 	 */
-	bool override_edid;
+	struct mutex edid_override_mutex;
+
 	/** @epoch_counter: used to detect any other changes in connector, besides status */
 	u64 epoch_counter;