[Intel-gfx] [regression] i915: enable AVI infoframe for intel_hdmi.c [v4]

[Alexey Fisher]

I have regression after commit "i915: enable AVI infoframe for
intel_hdmi.c [v4]". After boot i get black screen with cursor on top
left corner. I can access my pc per ssh.

My HW: Intel DG45ID board, Monitor (iiyama prolite b2409hds) connected
on DVI.

xrandr 
Screen 0: minimum 320 x 200, current 1920 x 1080, maximum 8192 x 8192
VGA1 disconnected (normal left inverted right x axis y axis)
HDMI1 disconnected (normal left inverted right x axis y axis)
DP1 disconnected (normal left inverted right x axis y axis)
HDMI2 connected 1920x1080+0+0 (normal left inverted right x axis y axis)
521mm x 293mm
   1920x1080      60.0*+
   1680x1050      60.0  
   1280x1024      75.0     60.0  
   1440x900       75.0     59.9  
   1280x960       60.0  
   1152x864       75.0  
   1024x768       75.1     70.1     60.0  
   832x624        74.6  
   800x600        72.2     75.0     60.3     56.2  
   640x480        72.8     75.0     66.7     60.0  
   720x400        70.1  
DP2 unknown connection (normal left inverted right x axis y axis)
   1360x768       59.8  
   1152x864       60.0  
   1024x768       60.0  
   800x600        60.3  
   640x480        59.9  



3c17fe4b8f40a112a85758a9ab2aebf772bdd647 is the first bad commit
commit 3c17fe4b8f40a112a85758a9ab2aebf772bdd647
Author: David Härdeman <david at hardeman.nu>
Date:   Fri Sep 24 21:44:32 2010 +0200

    i915: enable AVI infoframe for intel_hdmi.c [v4]
    
    This patch enables the sending of AVI infoframes in
    drivers/gpu/drm/i915/intel_hdmi.c.
    
    My receiver currently loses sync when the HDMI output on my computer
    (DG45FC motherboard) is switched from 800x600 (the BIOS resolution)
to
    1920x1080 as part of the boot. Fixable by switching inputs on the
receiver
    a couple of times.
    
    With this patch, my receiver has not lost sync yet (> 40 tries).
    
    Fourth version, now based on drm-intel-next from:
    git://git.kernel.org/pub/scm/linux/kernel/git/ickle/drm-intel.git
    
    Two questions still remain:
    
    I'm assuming that the sdvo hardware also stores a header ECC byte in
    the MSB of the first dword - is this correct?
    
    Does the SDVOB and SDVOC handling in intel_hdmi_set_avi_infoframe()
    look correct?
    
    Signed-off-by: David Härdeman <david at hardeman.nu>
    Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>