Hello,
I am personally affected by this bug, and so did my colleagues and
clients, in feisty, gutsy and hardy. So, we finally found some time to
look into it more deeply.
This bug is not very hardware specific. Our observation is that often
tools like krandrtray, displayconfig-gtk, xrandr work, but displayconfig
in kde-guidance does not. That hints at a software bug.
Our test configuration:
* Kubuntu 8.04 (i386)
* Intel Q35 chipset (display)
* SONY Trintron Multiscan E230 CRT Monitor
Test: Changing screen resolution using displayconfig from kde-guidance
in non-administrator mode.
With that configuration, displayconfig shows the following available
resolutions: 640x480, 720x400, 800x600, 832x624, 1024x768, 1280x960,
1280x1024, 1600x1200
However, we could only change to 640x480, 800x600 and 1024x768 directly.
Other resolutions didn't really work. Or did they? After changing from
1024x768 to, say, 1600x1200 (without manually setting the refresh rate),
the screen stays at 1024x768 with the 15-second timeout pop-up box, but
with the following error message in the console:
X Error: BadValue (integer parameter out of range for operation) 2
Major opcode: 156
Minor opcode: 2
Resource id: 0x4b
If I accept the resolution change, then kill X by Ctrl-Alt-Backspace,
and re-login, X is in 1600x1200!
Indeed, a quick check of ~/.kde/share/config/displayconfigrc reviews
that it has stored the setting of 1600x1200, and apparently /usr/bin
/displayconfig-restore (called by /etc/X11/Xsession.d/40guidance-
displayconfig_restore) is working!
Since both displayconfig and displayconfig-gtk use guidance-backend, and
yet one works and another does not, we became convinced the bug is *not*
in the backend, but somewhere in /usr/bin/displayconfig the frontend
itself.
Running xf86misc.py shows the following:
=================================================================
Number of screens: 1
Idle seconds: 0.059
Gamma:(1.0, 1.0, 1.0)
SizeID:0
Size:(1024, 768, 312, 234)
Available Sizes:[(1024, 768, 312, 234), (1600, 1200, 312, 234), (1280, 1024,
312, 234), (1280, 960, 312, 234), (1152, 864, 312, 234), (832, 624, 312, 234),
(800, 600, 312, 234), (640, 480, 312, 234), (720, 400, 312, 234)]
Rotation:1
Available Rotations:63
Refresh rate:75
Refresh rates for the current screen:[85, 75, 70, 60, 43]
All Refresh Rates:[85, 75, 70, 60, 43]
All Refresh Rates:[60]
All Refresh Rates:[75]
All Refresh Rates:[75]
All Refresh Rates:[85, 75]
All Refresh Rates:[75]
All Refresh Rates:[85, 72, 75, 60, 56]
All Refresh Rates:[85, 75, 73, 67, 60]
All Refresh Rates:[88, 70]
SizeID:0
Size:(1024, 768, 312, 234)
Available Sizes:[(1024, 768, 312, 234), (1600, 1200, 312, 234), (1280, 1024,
312, 234), (1280, 960, 312, 234), (1152, 864, 312, 234), (832, 624, 312, 234),
(800, 600, 312, 234), (640, 480, 312, 234), (720, 400, 312, 234)]
=================================================================
The default resolution is 1024x768 @ 85 Hz.
After some debugging, it turns out that: when trying to change to
1600x1200, even though displayconfig shows "60 Hz" (the only valid
refresh rate) selected in the combo box, upon clicking "Apply",
displayconfig actually tried to set the resolution to 1600x1200 @ 85 Hz,
and that's why the backend complained with an "X Error: BadValue
(integer parameter out of range for operation)".
Finally, I arrived at _fillRefreshCombo() in displayconfig:
def _fillRefreshCombo(self):
# Update refresh combobox
self.size_refresh_combo.clear()
for rate in self.current_screen.getAvailableRefreshRates():
self.size_refresh_combo.insertItem(i18n("%1 Hz").arg(rate))
self.size_refresh_combo.setCurrentItem(self.current_screen.getRefreshRateIndex())
It got the correct refresh rate(s) for a certain resolution using
self.current_screen.getAvailableRefreshRates(), but
setRefreshRateIndex() is never called. Well, there was a signal-slot
set up earlier in the code using
self.connect(self.size_refresh_combo,SIGNAL("activated(int)"),self.slotRefreshRateChange)
But that is not helpful in this case, since the QComboBox::activated()
signal "is not emitted if the item is changed programmatically, e.g.
using setCurrentItem()" -
http://doc.trolltech.com/3.3/qcombobox.html#activated
So, a manual call to setRefreshRateIndex() fixes the bug. A patch is
attached (kubuntu_32_displayconfig_update_refresh_rate.patch). I have
tested it on both hardy and feisty.
Hope this helps.
--
Anthony Fok
ThizLinux Software Co., Ltd.
Hong Kong - Shenzhen - Beijing, China
** Attachment added: "kubuntu_32_displayconfig_update_refresh_rate.patch: The
refresh rate was not actually updated for the selected resolution, so
resolution change may fail at times. Fixed."
http://launchpadlibrarian.net/14545494/kubuntu_32_displayconfig_update_refresh_rate.patch
--
displayconfig resolution change bug
https://bugs.launchpad.net/bugs/82279
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