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udldrmfb: Fix EDID not working with monitors with EDID extension blocks 

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 <hdegoede@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Dave Airlie <airlied@redhat.com>
This commit is contained in:
Hans de Goede 2013-01-11 12:08:56 +01:00 committed by Dave Airlie
parent 7d00813f68
commit c930812fe5
1 changed files with 8 additions and 0 deletions
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8
drivers/gpu/drm/udl/udl_connector.c
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@ -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);