From c876baa8a8eda4a9ffcc6bdc144bb9d0fc3397a0 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 8d9dc44f1f94..1230bc0ffb0d 100644 --- a/drivers/gpu/drm/udl/udl_connector.c +++ b/drivers/gpu/drm/udl/udl_connector.c @@ -59,6 +59,14 @@ static int udl_get_modes(struct drm_connector *connector) connector->display_info.raw_edid = (char *)edid; + /* + * 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); connector->display_info.raw_edid = NULL;