Re: Yet more display troubles with 2.6.15-rc5-mm2

[Jesper Juhl <jesper.juhl@gmail.com>]

On 12/12/05, Antonino A. Daplas <adaplas@gmail.com> wrote:
> Jesper Juhl wrote:
> > In addition to the problem I reported earlier about 2.6.15-rc5-mm2
> > hanging at boot with vga=791 I've just discovered another problem.
> >
> > If I boot with vga=normal (which is aparently all that works), then I
> > can boot up to a nice lain text login and run startx, but if I then
> > switch away from X back to a text console with ctrl+alt+f6 or if I
> > shut down X, then I'm presented with a completely garbled text mode
> > screen - flashing coloured blocks all over, random bits of text at
> > random locations etc.
> >
> > Also, when starting X, just before the cursor appears I normally just
> > have a black screen. With this kernel I first get a short blink of a
> > garbled graphics mode screeen with either what looks like just random
> > pixels or sometimes with something that looks like a mangled snapshot
> > of my text mode console, or if I kill X with ctrl+alt+backspace and
> > then start it again (the garbled text mode console does work, although
> > I'm glad I know how to touch type ;) then I sometimes get what looks
> > like a snapshot of my previous X session with random pixels on top.
> > The garbled graphical screen stays for just a blink of an eye, then
> > it's replaced with the normal black screen and the mouse cursor.
> >
> > 2.6.15-rc5-git1 works perfectly without these issues.
>
> I cannot reproduce your problem...
>

It's completely reproducable here when booting the kernel with  vga=normal
and then starting X with the attached xorg.conf using this grahics card :

# lspci -vvx
...
01:05.0 VGA compatible controller: Matrox Graphics, Inc. MGA Parhelia
AGP (rev 03) (prog-if 00 [VGA])
        Subsystem: Matrox Graphics, Inc. Parhelia 128Mb
        Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop-
ParErr- Stepping- SERR- FastB2B-
        Status: Cap+ 66Mhz+ UDF- FastB2B+ ParErr- DEVSEL=medium
>TAbort- <TAbort- <MAbort- >SERR- <PERR-
        Latency: 64 (4000ns min, 8000ns max), cache line size 08
        Interrupt: pin A routed to IRQ 4
        Region 0: Memory at e8000000 (32-bit, prefetchable) [size=128M]
        Region 1: Memory at e5000000 (32-bit, non-prefetchable) [size=8K]
        Expansion ROM at e7fe0000 [disabled] [size=128K]
        Capabilities: [dc] Power Management version 2
                Flags: PMEClk- DSI+ D1- D2- AuxCurrent=0mA
PME(D0-,D1-,D2-,D3hot-,D3cold-)
                Status: D0 PME-Enable- DSel=0 DScale=0 PME-
        Capabilities: [f0] AGP version 2.0
                Status: RQ=32 Iso- ArqSz=0 Cal=0 SBA+ ITACoh- GART64-
HTrans- 64bit- FW+ AGP3- Rate=x1,x2,x4
                Command: RQ=1 ArqSz=0 Cal=0 SBA- AGP- GART64- 64bit-
FW- Rate=<none>
00: 2b 10 27 05 07 00 b0 02 03 00 00 03 08 40 00 00
10: 08 00 00 e8 00 00 00 e5 00 00 00 00 00 00 00 00
20: 00 00 00 00 00 00 00 00 00 00 00 00 2b 10 40 08
30: 00 00 fe e7 dc 00 00 00 00 00 00 00 04 01 10 20

note that if I use a fb console everything is fine, only when booting
initially with vga=normal is there a problem.


> If set, can you comment out Load "dri" and/or Load "glx" from your
> X config?
>
Both were set. Commenting out both didn't change a thing.


> Can you try another X driver, ie, vesa?
>
I'm already using the vesa driver. It seems to be the only Open Source
driver that'll work with this card, so i don't have any other to try.

> Also, these 2 patches are present in mm but not in Linus' tree.  Can
> you check which of these are the culprit, if any?
>
> http://kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.15-rc2/2.6.15-rc2-mm1/broken-out/vgacon-fix-doublescan-mode.patch
> http://kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.15-rc2/2.6.15-rc2-mm1/broken-out/vgacon-workaround-for-resize-bug-in-some-chipsets.patch
>

Since this is 2.6.15-rc5-mm2 I grabbed these two instead:
http://kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.15-rc5/2.6.15-rc5-mm2/broken-out/vgacon-fix-doublescan-mode.patch
http://kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.15-rc5/2.6.15-rc5-mm2/broken-out/vgacon-workaround-for-resize-bug-in-some-chipsets.patch

Reverting both patches didn't fix the problem. Starting X then
switching back to a text mode console still results in a completely
messed up text console. X is fine, I can switch back to it no problem,
but text consoles go bye-bye...

Would there be any point in trying a kernel with just one of the
patches reverted?


--
Jesper Juhl <jesper.juhl@gmail.com>
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