Red Hat Bugzilla – Bug 719728
Mobility Radeon X700 screen garbage
Last modified: 2012-08-07 15:13:16 EDT
Created attachment 511783 [details]
Description of problem:
About every 10th reboot I see garbage on the screen with the X700. Picture attached. Power-cycling and the problem goes away. Still it's annoying.
Version-Release number of selected component (if applicable):
about every 10th reboot
Steps to Reproduce:
1. happens when the screen resolution is changed during boot
screen is distorted
Created attachment 511785 [details]
Created attachment 511786 [details]
First try a newer kernel (2.6.39 and 3.0). Also, does a VT switch help? Beyond that, we can try comparing register dumps using radeonreg when the screen is working properly and not working properly. radeonreg is available here:
radeonreg regs radeon > working.regs
radeonreg regs radeon > broken.regs
And attach the dumps here.
Created attachment 511886 [details]
Created attachment 511888 [details]
VT switching makes no difference, once it's screwed it doesn't go away.
2.6.39 shows the same behaviour, haven't checked 3.0 yet. If you think it's worth to try latest 3.0 I'll do that.
The two sets of registers are identical. The only differences are counter regs which aren't relevant. As such, it's probably a timing issue. I'm assuming you are seeing the problem on the LVDS panel? LVDS is very picky about programming timing. Does forcing a DPMS cycle fix it?
xset dpms force off
You can also look at adjusting or adding delays at various points in radeon_legacy_lvds_update() and radeon_legacy_lvds_mode_set() in radeon_legacy_encoders.c in the kernel.
(In reply to comment #7)
> I'm assuming you are seeing the problem on the LVDS panel?
> programming timing. Does forcing a DPMS cycle fix it?
> xset dpms force off
Screen turns off for about 1 sec, turns back on but the issue remains. Tried several times.
> You can also look at adjusting or adding delays at various points in
> radeon_legacy_lvds_update() and radeon_legacy_lvds_mode_set() in
> radeon_legacy_encoders.c in the kernel.
I'll give it a try.
Btw, sometimes when coming out of suspend the backlight is not turned back on. Could this be related?
(In reply to comment #8)
> > programming timing. Does forcing a DPMS cycle fix it?
> > xset dpms force off
> Screen turns off for about 1 sec, turns back on but the issue remains. Tried
> several times.
sleep 5; xset dpms force off
> Btw, sometimes when coming out of suspend the backlight is not turned back on.
> Could this be related?
Possibly, but I doubt it. Backlight is controlled via ACPI or a platform specific backlight driver.
I looked at radeon_legacy_lvds_update() and radeon_legacy_lvds_mode_set() but I'm not sure where to add delays and how long they should be. Could you give me some hints? Thanks!
sleep 5; xset dpms force off
That turned the screen off but once a button is pressed the screen turns back on and the problem persists.
However I recognized that during hibernate the screen turns black shortly before switching to the console where the hibernate messages are printed. And this VT switch fixes it, but a normal VT switch does not.
Almost forgot I also found a workaround using lxrandr
lxrandr show 2 frequencies 60,0 Hz and 60,2 Hz, default being 60,2 Hz. Switching frequencies seems to re-init the display and the screen distortion goes away.
Can you attach the output of xrandr --verbose?
Created attachment 515226 [details]
I ran xrandr --verbose twice, once when the screen is distorted and another time when it's fine.
The only difference is the timestamp.
@@ -12,7 +12,7 @@
load detection: 1 (0x00000001) range: (0,1)
LVDS connected 1400x1050+0+0 (0x55) normal (normal left inverted right x axis y axis) 0mm x 0mm
- Timestamp: 100452
+ Timestamp: 83129831
Subpixel: horizontal rgb
I've seen this on my new fusion netbook as well now.
That one got a 1002:9802 GPU. Only happened once so far.
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