From 513c651beebdffa05fd7f4fa0221ea18edba6ad3 Mon Sep 17 00:00:00 2001 From: Hans de Goede Date: Fri, 11 Jan 2013 12:08:56 +0100 Subject: [PATCH] udldrmfb: Fix EDID not working with monitors with EDID extension blocks commit c930812fe5ebe725760422c9c351d1f6fde1502d upstream. udldrmfb only reads the main EDID block, and if that advertises extensions the drm_edid code expects them to be present, and starts reading beyond the buffer udldrmfb passes it. Although it may be possible to read more EDID info with the udl we simpy don't know how, and even if trial and error gets it working on one device, that is no guarantee it will work on other revisions. So this patch does a simple fix in the form of patching the EDID info to report 0 extension blocks, this fixes udldrmfb only doing 1024x768 on monitors with EDID extension blocks. Signed-off-by: Hans de Goede Signed-off-by: Dave Airlie Signed-off-by: Greg Kroah-Hartman --- drivers/gpu/drm/udl/udl_connector.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/drivers/gpu/drm/udl/udl_connector.c b/drivers/gpu/drm/udl/udl_connector.c index b3b2cedf6745..86538c983542 100644 --- a/drivers/gpu/drm/udl/udl_connector.c +++ b/drivers/gpu/drm/udl/udl_connector.c @@ -57,6 +57,14 @@ static int udl_get_modes(struct drm_connector *connector) edid = (struct edid *)udl_get_edid(udl); + /* + * We only read the main block, but if the monitor reports extension + * blocks then the drm edid code expects them to be present, so patch + * the extension count to 0. + */ + edid->checksum += edid->extensions; + edid->extensions = 0; + drm_mode_connector_update_edid_property(connector, edid); ret = drm_add_edid_modes(connector, edid); kfree(edid); -- 2.39.5