drm/debugfs: add an "edid_override" file per connector

Add a file to debugfs for each connector to allow the EDID to be
overridden.

v2: Copy ubuf before accessing it and reject invalid length data. (David
    Herrmann)
    Ensure override_edid is reset when a new EDID value is written.
    (David Herrmann)
    Fix the debugfs file permissions. (David Herrmann)

Signed-off-by: Thomas Wood <thomas.wood@intel.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

1 files changed, 8 insertions, 1 deletions

diff --git a/drivers/gpu/drm/drm_probe_helper.c b/drivers/gpu/drm/drm_probe_helper.c
index d22676b89cbb..db7d250f7ac7 100644
--- a/drivers/gpu/drm/drm_probe_helper.c
+++ b/drivers/gpu/drm/drm_probe_helper.c
@@ -130,7 +130,14 @@ static int drm_helper_probe_single_connector_modes_merge_bits(struct drm_connect
         count = drm_load_edid_firmware(connector);
         if (count == 0)
 #endif
-                count = (*connector_funcs->get_modes)(connector);
+        {
+                if (connector->override_edid) {
+                        struct edid *edid = (struct edid *) connector->edid_blob_ptr->data;
+
+                        count = drm_add_edid_modes(connector, edid);
+                } else
+                        count = (*connector_funcs->get_modes)(connector);
+        }
 
         if (count == 0 && connector->status == connector_status_connected)
                 count = drm_add_modes_noedid(connector, 1024, 768);