Bug 16957

Summary: [855GM] X hangs on startup in i830_crt_detect(), with patch "force-enables pipe A"
Product: xorg Reporter: Andrew Moise <chops>
Component: Driver/intelAssignee: Jesse Barnes <jbarnes>
Status: VERIFIED FIXED QA Contact: Xorg Project Team <xorg-team>
Severity: normal    
Priority: medium Keywords: NEEDINFO
Version: 7.3 (2007.09)   
Hardware: x86 (IA32)   
OS: Linux (All)   
Whiteboard:
i915 platform: i915 features:
Attachments:
Description Flags
Xorg.0.log
none
xorg.conf none

Description Andrew Moise 2008-08-01 21:37:14 UTC
I'm running a small-form-factor PC with an 855GM chipset, and X hangs during startup leaving me with a blank screen on my VGA output.  This happens in 2.4.0 from git, in the current git head (commit 27e9506fda86e90fd67de1715fa32d23aaa8a683), and in 2.3.2-2+lenny1 from Debian sid.  It does _not_ happen in 2.3.2-2+lenny2, and the only difference between those two is that 2.3.2-2+lenny1 includes a cherry-picked patch from 2.4.0 that force-enables pipe A on 855GM, and 2.3.2-2+lenny2 doesn't.

This is the backtrace I get from gdb when attaching to the hung X process (using the git head version of the intel driver):

0xb7b0a5da in i830_crt_detect (output=0x9db1818) at i830_crt.c:285
285             while ((dsl = INREG(pipe_dsl_reg)) <= vsample)
(gdb) bt
#0  0xb7b0a5da in i830_crt_detect (output=0x9db1818) at i830_crt.c:285
#1  0x080f64b0 in xf86ProbeOutputModes (scrn=0x9daf0e0, maxX=2048, maxY=2048)
    at ../../../../hw/xfree86/modes/xf86Crtc.c:1275
#2  0x080f6e24 in xf86InitialConfiguration (scrn=0x9daf0e0, canGrow=0)
    at ../../../../hw/xfree86/modes/xf86Crtc.c:1577
#3  0xb7b15d10 in I830PreInit (pScrn=0x9daf0e0, flags=<value optimized out>)
    at i830_driver.c:1645
#4  0x080ab42f in InitOutput (pScreenInfo=0x8210bc0, argc=3, argv=0xbf9a6f84)
    at ../../../../hw/xfree86/common/xf86Init.c:548
#5  0x08074591 in main (argc=3, argv=0xbf9a6f84, envp=0xbf9a6f94)
    at ../../dix/main.c:369
(gdb)

I'm running the core server version 1.4.2-2 from Debian sid.  I'll attach my config and log.

Cheers.
Comment 1 Andrew Moise 2008-08-01 21:38:48 UTC
Created attachment 18072 [details]
Xorg.0.log
Comment 2 Andrew Moise 2008-08-01 21:39:12 UTC
Created attachment 18073 [details]
xorg.conf
Comment 3 Andrew Moise 2008-08-01 21:44:57 UTC
There's also a separate bug in Debian's bug tracker describing this problem on a laptop: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=493096
Comment 4 Gordon Jin 2008-08-01 23:29:49 UTC
reassign to Jesse.
Comment 5 Jesse Barnes 2008-08-06 14:32:43 UTC
Can you see what vsample value it's waiting for at that point?  It looks like the current logic is tight in that it can result in a border size of 1, but it should eventually work...

In the meantime I'll try hooking a monitor to my 855 laptop and seeing what happens.
Comment 6 Jesse Barnes 2008-08-06 14:59:15 UTC
I can't reproduce on my 855 laptop...  can you enable the modedebug option and attach a new log?
Comment 7 Michael Fu 2008-09-25 01:48:19 UTC
ping bug reporter...
Comment 8 Andrew Moise 2008-09-27 17:17:26 UTC
Sadly, I don't have time to respond to my xorg bugs with anything like reasonable speed anymore.  See my comments in bug #11368 for more.
Comment 9 Andrew Moise 2008-11-19 22:03:40 UTC
Hm, this doesn't seem to happen in 2.4.2-1 from Debian experimental.  I'm fine with assuming it got fixed since 2.4.0.

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