[Openchrome-users] CN700 problem, more details

[Christiaan van Dijk]

Hi all,

not planning on giving up yet on the CN700 board.I think it can be fixed 
but will need some effort. At least I'm not the only one having these 
problems and I can reproduce the problems very easily.

Here's my latest status. I'm running Openchrome rev. 255 again. With DRI 
enabled it's very easy to crash the system (mplayer (only XV) running, 
starts dropping frames, crashes X). Rev 252 does not crash at this 
point. Only driver changes of importance are in the order of 
VIADRIRingBufferInit(pScrn) and viaDRIOffscreenRestore(pScrn) in 
via_driver.c.

Anyway, I thought this could be a DMA issue, tried "EnableAGPDMA" 
"false" in xorg.conf but no change. Looking through the source code of 
the driver I noticed the option "NoXVDMA", when this option is set to 
"true" the system no longer crashes on mplayer anymore! But I also get 
the alarming dmesg messages on HDD errors, like (old example, got same 
message):

Dec  5 18:11:21 HTPC-2 kernel: hda: dma_intr: status=0x51 { DriveReady 
SeekComplete Error }
Dec  5 18:11:21 HTPC-2 kernel: hda: dma_intr: error=0x84 { 
DriveStatusError BadCRC }
Dec  5 18:11:21 HTPC-2 kernel: ide: failed opcode was: unknown

Interesting detail; if I disable DMA completely for the HDD I still get 
this same error message. This makes me believe these messages are a side 
effect of something else going wrong. I can get rid of the messages by 
not loading the DRI module in xorg.conf, but also losing XvMC :-( .


Now things become even more interesting. The system is very slow, X 
seems to take big chunks of CPU load but is not doing anything (checked 
this with system power consumption which is close to idle). Also a VNC 
session from another computer is very slow. Playing a divx with mplayer 
results in huge amount of dropped frames within a couple of seconds 
playing. Pause/resume lets mplayer catch up in no time but after a 
couple of seconds same story.
If there however is another task running which does regular screen 
output (local or remote VNC session( :-! )) the system keeps on playing 
smoothly without dropping a frame. Tried this with glxgears (no dri, 
full software) and kmonitor, this is not the best check but I couldn't 
think of a simple app. only putting something on the screen. Hang on, 
just tried xclock -analog -update 1, result; mplayer drops frames. So it 
does not seem to be specific screen XV IO but more system 
IO/mem/whatever related, also explains why a VNC session on a remote 
machine has the same result.

Well, I'm running out of ideas, really need some help on this point, are 
there other options I can experiment with, already tried various 
combinations with:

"DisableIRQ"     -> Disabling IRQ makes the system way more sensitive to 
the HDD errs.
"EnableAGPDMA"   -> No effect
"NoAGPFor2D"     -> No effect
"NoXVDMA"        -> Resolves the crashes but gives the HDD errs.
And the loading/not loading of the dri module.

Would really like to get this problem solved, system is 100% available 
for testing (building a test system for experimenting is proving very 
useful :-) ). Any idea is welcome, I've gotten no experience with 
debugging this system but always happy to learn.

Regds,
Christiaan van Dijk.