Different color depths per head by default?

Alex Deucher alexdeucher at gmail.com
Tue Sep 15 07:19:58 PDT 2009

2009/9/13 Csillag Kristof <csillag.kristof at united-consult.hu>:
> Dear all,
> I have encountered another weird thing when setting up my displays.
> On X startup, the gradient background image of the login
> screen fills up both screens (as it should).
> On the right monitor (connected to DVI-0), the gradient is continuous,
> but on the left one (connected to DVI-1), large stripes are visible.
> Previously, I seen such stripes when I was using 16bpp
> (instead of 24 or 32bpp), but in the current configuration,
> I have not done anything to configure the color depth,
> so I would except that everything comes up in full true color.
> There is 64Mb of RAM available on the FireMV 2400 card,
> so video RAM should not be a problem this time.
> I have taken a look in the resulting X log, but I could not find
> any sign of using 16bpp... still, it is painfully obvious from
> the picture I see.
> (If I put up any gradient image, the difference is obvious.)
> The same problem only appears in single screen mode with DVI-1.
> Do you have any idea what could be the reason for this?

It's the same color depth if you are using xrandr.  It's likely a
problem with the gamma settings for the crtc driving DVI-1 or the
dither setup is wrong for the tmds transmitter used for DVI-1.  Does
playing with the gamma via xgamma or xrandr fix it?


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