drm: Separate EDID Header Check from EDID Block Check

    Provides function drm_edid_header_is_valid() for EDID header check
    and replaces EDID header check part of function drm_edid_block_valid()
    by a call of drm_edid_header_is_valid().
    This is a prerequisite to extend DDC probing, e. g. in function
    radeon_ddc_probe() for Radeon devices, by a central EDID header check.

    Tested for kernel 2.6.35, 2.6.38 and 3.0

Cc: <stable@kernel.org>
Signed-off-by: Thomas Reim <reimth@gmail.com>
Reviewed-by: Alex Deucher <alexdeucher@gmail.com>
Acked-by: Stephen Michaels <Stephen.Micheals@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
index d515bc8..44335e5 100644
--- a/include/drm/drm_crtc.h
+++ b/include/drm/drm_crtc.h
@@ -804,6 +804,7 @@
 extern int drm_add_modes_noedid(struct drm_connector *connector,
 				int hdisplay, int vdisplay);
 
+extern int drm_edid_header_is_valid(const u8 *raw_edid);
 extern bool drm_edid_is_valid(struct edid *edid);
 struct drm_display_mode *drm_mode_find_dmt(struct drm_device *dev,
 					   int hsize, int vsize, int fresh);