[Openchrome-devel] K8M800 artifacts, trac #145, trac #164

[Gabriel Mansi]

On Tue, 2008-03-18 at 20:13 +0100, Thomas Hellstr?m wrote:
> 
> There'll be some more optimizing / stablizing work for AGP DMA in a
> week 
> or so, but I'll ask Dave not to push anything until it's considered 
> stable. I think the code in DRM now is reasonably stable but not
> really 
> optimal.
> 
> That AGP command reader is really screwed. There's a register that
> you 
> read to determine where it is currently reading. Locations that are 
> newly read by the command reader can supposedly be reused for new
> data....
> 
> However every now and again the register shows that the command
> reader 
> has read "too far", and then suddenly it goes in the reverse
> direction.....

I found that reg_pause_addr in via_dri.c was incorrectly assigned to
0x40c instead of 0x418 for the CX700:
http://www.openchrome.org/trac/changeset/556
With the wrong pause address register I was getting a lot of messages
like this:

[drm:via_hook_segment] *ERROR* Paused at incorrect address. 0xf1edb500,
0xf1eda500 0x00000000
[drm:via_hook_segment] *ERROR* Paused at incorrect address. 0xf1edc500,
0xf1eda500 0x00000000
[drm:via_hook_segment] *ERROR* Paused at incorrect address. 0xf1edd500,
0xf1eda500 0x00000000

I wonder if the other chipsets (VM800 and PM800) should be using that
register as well. VIA is using 0x418 for all chipsets.

Regards,
Gabriel.