Failing via_cmdbuf_wait

Failing via_cmdbuf_wait

[Robert Högberg]

Hello.

I'm trying to debug an issue I'm having with my Via CN400 board. The problem I see is that every time I watch a specific DVD using XvMC the display freezes completely after a short time.

The freeze seems to be caused by a failing via_cmdbuf_wait. I don't understand why it fails, but it fails with the error message:
*ERROR* via_cmdbuf_wait timed out hw 32700 cur_addr 400 next_addr 87678

And all following calls give the same output. It never recovers.

Any ideas where I should look now? If the buffer isn't emptied as expected, is it a hardware problem? There seems to be no error handling in via_cmdbuf_jump if via_cmdbuf_wait fails. Is it missing or is this situation so fatal that it can't be fixed or is it ok to just move along and ignore the problem?

There's also a pretty huge delay inside via_cmdbuf_wait. In a worst case scenario it will sleep 1000000*1ms (1000 seconds). Is that how it should be? Seems strange to me.

All hints are appreciated!

/Robert

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Re: Failing via_cmdbuf_wait

[Thomas Hellstrom]

Robert Högberg wrote:
> Hello.
>
> I'm trying to debug an issue I'm having with my Via CN400 board. The problem I see is that every time I watch a specific DVD using XvMC the display freezes completely after a short time.
>
> The freeze seems to be caused by a failing via_cmdbuf_wait. I don't understand why it fails, but it fails with the error message:
> *ERROR* via_cmdbuf_wait timed out hw 32700 cur_addr 400 next_addr 87678
>
> And all following calls give the same output. It never recovers.
>
> Any ideas where I should look now? If the buffer isn't emptied as expected, is it a hardware problem? There seems to be no error handling in via_cmdbuf_jump if via_cmdbuf_wait fails. Is it missing or is this situation so fatal that it can't be fixed or is it ok to just move along and ignore the problem?
>
> There's also a pretty huge delay inside via_cmdbuf_wait. In a worst case scenario it will sleep 1000000*1ms (1000 seconds). Is that how it should be? Seems strange to me.
>
> All hints are appreciated!
>
> /Robert
>   

Hi, Robert.

What you're seeing is a GPU hang, Either because of a bug in the kernel 
module or perhaps a hardware bug. The AGP DMA code is a bit shaky in the 
via drm. That has been fixed in the experimental openChrome drm, (but 
that driver suite doesn't support XvMC yet). The fixes haven't been 
ported over.

/Thomas
 




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