Bug 109654

Summary: Nouveau picks bad mode setting 640x480 resolution
Product: xorg Reporter: Dan Espen <dan1espen>
Component: Driver/nouveauAssignee: Nouveau Project <nouveau>
Status: RESOLVED NOTOURBUG QA Contact: Xorg Project Team <xorg-team>
Severity: normal    
Priority: medium    
Version: 7.7 (2012.06)   
Hardware: x86-64 (AMD64)   
OS: Linux (All)   
Whiteboard:
i915 platform: i915 features:
Attachments:
Description Flags
monitor edid none

Description Dan Espen 2019-02-16 18:46:05 UTC 
This has been discussed on the Nouveau mailing list.

When running this command:

xrandr -s 640x480

Nouveau only fills the screen horizontally, vertically it leaves 2/3s of the screen at the top and bottom unused.  This makes this mode unusable.

Adding -r 75 to the above command fixes the problem.

Perhaps the higher frequency mode should be used by default.

The NVIDIA drivers do not have this problem, the screen is always filled.

This bug breaks games like "lbrickbuster2" which want to run full screen at 640x480.
Comment 1 Ilia Mirkin 2019-02-16 20:07:01 UTC 
Created attachment 143385 [details]
monitor edid

Nouveau doesn't pick these things -- it does what it's told.

It does, however, allow it. Sounds like something about the monitor should make that illegal, but it's unclear what that would be.

Attaching EDID sent via ML. The interesting bits decode as

Established timings supported:
  720x400@70Hz 9:5 HorFreq: 31469 Hz Clock: 28.320 MHz
  640x480@60Hz 4:3 HorFreq: 31469 Hz Clock: 25.175 MHz
  640x480@75Hz 4:3 HorFreq: 37500 Hz Clock: 31.500 MHz
  800x600@60Hz 4:3 HorFreq: 37900 Hz Clock: 40.000 MHz
  800x600@75Hz 4:3 HorFreq: 46900 Hz Clock: 49.500 MHz
  1024x768@60Hz 4:3 HorFreq: 48400 Hz Clock: 65.000 MHz
  1024x768@75Hz 4:3 HorFreq: 60000 Hz Clock: 78.750 MHz
  1280x1024@75Hz 5:4 HorFreq: 80000 Hz Clock: 135.000 MHz
Standard timings supported:
  1920x1080@60Hz 16:9
  1600x1200@60Hz 4:3 HorFreq: 75000 Hz Clock: 162.000 MHz
  1280x1024@60Hz 5:4 HorFreq: 64000 Hz Clock: 108.000 MHz
  1280x800@60Hz 16:10
  1152x864@75Hz 4:3 HorFreq: 67500 Hz Clock: 108.000 MHz

CTA extension block
Extension version: 3
25 bytes of CTA data
  Video data block
...
    VIC   3 720x480@60Hz 16:9  HorFreq: 31469 Hz Clock: 27.000 MHz
    VIC   2 720x480@60Hz 4:3  HorFreq: 31469 Hz Clock: 27.000 MHz
    VIC   1 640x480@60Hz 4:3  HorFreq: 31469 Hz Clock: 25.175 MHz


So it certainly seems like 640x480@60 should work OK.
Comment 2 Dan Espen 2019-02-17 02:25:43 UTC 
Changing status to resolved.

I reinstalled the NVIDIA drivers, did an lsmod and noticed module "nvidia_modeset" running.
I think that explains why I get different behavior with and without nouveau.

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