Question about enabling deep color support

Alex Deucher alexdeucher at
Wed Sep 17 06:49:04 PDT 2014

On Fri, Sep 12, 2014 at 11:37 AM, Patrick Voigt <patrick-voigt at> wrote:
> Hello,
>   I wanted to give the deep color support a try. I installed the kernel 3.16
> and set the kernel module parameter deep_color=1. That seemed to work since
> I see the following:
> pvoigt at bart:~$ more
> /sys/class/drm/card0/device/driver/module/holders/radeon/parameters/deep_color
> 1
> pvoigt at bart:~$
> OK, fine. But when I start X now, xdpyinfo doesn't give me any visual with a
> bit depth of 10 per color. So my question is: What am I missing? Does it
> only work when using a HDMI connection?
> I attached the Xorg.log and output of xdpyinfo.
> My hardware: AMD Firepro 4900 card, NEC SpectraView 241 monitor connected
> via Displayport
> I tried the binary fglrx driver, and I do get visuals with 30 bit (10 bit
> per color).

It currently only works for HDMI and additional patches for the
userspace drivers are required for those visuals.  Support for pre-SI
asics is available here:
Support for SI+ asics still needs to be implemented.

Those patches should work with your chip if you are using HDMI.


> Thank you!
> Patrick
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