could use help debugging black screen on RS780 (xf86-video-ati-6.13.0, radeon)

Alex Deucher alexdeucher at
Tue Jun 1 17:46:56 PDT 2010

On Tue, Jun 1, 2010 at 8:32 PM, Larry Doolittle <larry at> wrote:
> Ross -
> On Tue, Jun 01, 2010 at 10:09:21AM -0400, Ross Vandegrift wrote:
>> On Mon, May 31, 2010 at 09:52:37PM -0700, Larry Doolittle wrote:
>> > ... screens go black when I start the X server.
>> I've recently been seeing this symptom as well.  Same Debian release,
>> ATI RS880 video.  Maybe 10% of the time, when returning from video
>> suspend, the screen contents come up for approximately a second and
>> then the monitor goes blank.  Switching to a text VT and back fixes
>> the issue.
>> Only seems to be triggered on startup and return from power saving
>> mode.
> My black-screen is 100% reliable.  Maybe the underlying cause is
> similar, but the symptoms sound different to me.  I never see
> anything, not even for a second.  OTOH, maybe there is something
> there for a second but my monitor doesn't sync to it in time.
> Just for kicks, I installed the firmware-linux-nonfree package,
> so the kernel could have those radeon microcode files if it wanted.
> It didn't help.  I don't see the RS780 on the list of files at
> except generically in the R700-family.
> I only have access to this computer for a limited number of hours
> in the day, so my debugging iterations may be slow.
> I have assumed that the problem is in the hardware-dependent
> xf86-video-ati-6.13.0 module.  Is there any point in trying
> more recent versions of the X server itself?  Squeeze runs
> xserver-xorg-core based on xorg-server_1.7.7 .

You might try using the old PLL code:
Option "NewPLL" "False"
in the device section of your config.  Do any modes besides 2048x1152 work?
It's probably also worth trying kms.


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