drm/ast something ate high-res modes (5.3->5.6 regression)

[Ilpo Järvinen]

Hi,

After upgrading kernel from 5.3 series to 5.6.16 something seems to 
prevent me from achieving high resolutions with the ast driver.

With 5.6.16:

$ xrandr
Screen 0: minimum 320 x 200, current 1600 x 1200, maximum 1920 x 2048
VGA-1 connected primary 1600x1200+0+0 (normal left inverted right x axis y axis) 519mm x 324mm
   1600x1200     60.00* 
   1680x1050     59.95  
   1280x1024     75.02    60.02  
   1440x900      59.89  
   1280x800      59.81  
   1024x768      75.03    60.00  
   800x600       75.00    60.32  
   640x480       75.00    59.94  
   1920x1200_60.0  59.95  

If I try to change to that manually added high-res mode, I get:
xrandr: Configure crtc 0 failed

With 5.3 series I've this:

Screen 0: minimum 320 x 200, current 1920 x 1200, maximum 1920 x 2048
VGA-1 connected primary 1920x1200+0+0 (normal left inverted right x axis y axis) 519mm x 324mm
   1920x1200     59.95*+
   1600x1200     60.00  
   1680x1050     59.95  
   1280x1024     75.02    60.02  
   1440x900      59.89  
   1280x800      59.81  
   1024x768      75.03    60.00  
   800x600       75.00    60.32  
   640x480       75.00    59.94  
   1920x1200_60.0  59.95  

As I've had issues in getting EDID reliably from the monitor, I provide it 
on kernel command-line (the one dumped from the monitor I use). In 
addition, I've another workaround for past issues related to EDID which 
always adds that 1920x1200_60.0 mode but now I cannot use even it to
enter a high-res mode.

If you need some additional info or want me to test a patch, just let me 
know (but some delay is expected in testing patches). Thanks.


-- 
 i.