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

Thomas Hellström thomas
Wed Mar 19 13:55:53 PDT 2008

Gabriel Mansi wrote:
> 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.
I'm running a CX700-M2 without obvious problems with 0x40C, but I'll 
check tomorrow with 0x418. The PM800 and CN400 both worked well with 
0x40C when I tried the last time.


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