[Bug 18370] Monitor refresh rate not set correctly

[bugzilla-daemon at freedesktop.org]

http://bugs.freedesktop.org/show_bug.cgi?id=18370





--- Comment #6 from Alex Deucher <agd5f at yahoo.com>  2008-11-06 12:44:30 PST ---
(In reply to comment #5)
> Sorry no success with it. Problems which I don't understand:
> 
> 1. As discribed in the wiki, randr 1.2 support is already included in X.org 
> ver. 1.3, which is working fine

yes, but the version of the radeon driver you are using with xserver 1.3 is not
xrandr 1.2 aware.  It's an older version of the driver that does not support
xrandr 1.2.

> 2. Im not able to delete an unwanted mode with xrandr:
> root at lisa:~# xrandr --delmode VGA-0 "1920x1200"
> X Error of failed request:  BadAccess (attempt to access private resource 
> denied)
>   Major opcode of failed request:  156 (RANDR)
>   Minor opcode of failed request:  19 ()
>   Serial number of failed request:  15
>   Current serial number in output stream:  16

You probably have an old version of the xrandr utility or the xrandr headers
from before --delmode was added.

> 
> 3. with x.org ver.1.4.2 after every resoltion switch I get a default refresh 
> rate of 60Hz (versus 75 Hz in ver. 1.3). I can change it to 75 Hz afterwards 
> with xrandr, but that is not what I want.

Since you monitor does not provide an edid there is no way to know what it's
"Preferred" mode is so the xserver guesses based on the sync ranges and mode in
your screen section.  See the "Forcing a preferred mode" section of this page
for info on how to specify your preferred mode with randr 1.2:
http://wiki.debian.org/XStrikeForce/HowToRandR12

> 
> 4. for every xrandr-command i get two short flickerings of my monitor (black 
> monitor) with ver. 1.4.2. (not with 1.3), this also happens for every change 
> of monitor resolution or at start of a wine application. I guess, my monitor 
> does ist, while it is accesed with DDC. Thats why I want to disable DDC 
> completely an use my hard coded modes, but the DDC-modes are still there in 
> ver. 1.4.2 (working in 1.3) and it seems, that the monitor capabilities are 
> verified via DDC for every change of resulution in ver. 1.4.2. (that's why 
> the black screen??). Is it somehow possible to disable DDC completely? 
> (settings in xorg.conf don't seem to work any longer in ver. 1.4.2)
> 

It's not DDC that's causing the flickering, it's load detection.  Dynamic
reconfiguration only came along with xrandr 1.2 compatible versions of the
driver.  Unfortunately, your monitor does not provide an edid, so ddc doesn't
work.  As such the driver falls back to using load detection to detect if a
monitor is attached or not.  This is required in your case as the monitor does
not seem to have an edid.

This didn't happen with older version of the driver since, they did not support
dynamic reconfiguration.  In the old version, the driver detected the attached
displays once at start up and that was it.  Once the driver was up there way no
way to dynamically turn an output on or off, etc.


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