The driver caches a copy of the edid in the driver connector structure (radeon_connector->edid) when it it reads the edid from the monitor via the get_modes() or detect() connector callbacks. When you provide a user supplied edid, the driver's copy never gets updated since no additional driver callbacks are called. It should be handled properly on my 3.17-wip branch: http://cgit.freedesktop.org/~agd5f/linux/log/?h=drm-next-3.17-wip