[Bug 17215] Screen resolution issues with Radeon Mobility 7500 unless NoDDC specified

[bugzilla-daemon at freedesktop.org]

http://bugs.freedesktop.org/show_bug.cgi?id=17215





--- Comment #3 from Alex Deucher <agd5f at yahoo.com>  2008-08-22 07:01:35 PST ---
Created an attachment (id=18465)
 --> (http://bugs.freedesktop.org/attachment.cgi?id=18465)
Always add the screen modes to LVDS

(In reply to comment #2)
> Ah, thanks for the explanation!
> 
> But why does NoDDC make it work for these guys?  I'd have expected the opposite
> based on this description.

Because in that case the driver ignores the edid and just adds the modes
defined in the screen section which may include non-native modes.

> 
> Also, if EDID only gives one resolution and the scaler should be used for the
> others, why aren't scaled resolutions provided through xrandr in this case?
> 

We rely on the EDID unless it's not available.  The question is which modes
should we add by default? 800x600? 1024x768? 1152x864?  I suppose we could
always add the screen modes even when an EDID is present (maybe just for LVDS).
 I'm not sure what the best solution is.  The attached patch always adds the
modes specified in the screen section to LVDS outputs.

Note that users can still add new modes at runtime using xrandr:
xrandr --newmode 800x600   38.25  800 832 912 1024  600 603 607 624 -hsync
+vsync
xrandr --addmode LVDS 800x600


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