xf86-video-chips PPC multi-head for embedded
Donald Kayser
postman at kayser.net
Thu Apr 30 06:59:27 PDT 2009
Hello All,
I am currently working to support a multi-head adapter on an embedded
PPC with an Asiliant/C&T 69030. I have been debugging the driver and
have a fundamental issue that either I don't understand, or is wrong
in the code. The driver will load just fine with only one Screen
section in the xorg.conf file, but as soon as a second Screen section
is added, the xf86-video-chips driver reports a timeout. This timeout
is due to the BitBlt registers indicating that the BitBlt engine is
busy. As I have studied and debugged the code and compared it with the
data sheet, I have found that the driver never accesses the Pipeline B
through the area mapped to Pipeline B. In fact, all of the access to
both Pipelines is handled through the memory space of Pipeline A. This
is fundamentally OK as far as I can tell, but I have not been able to
determine how the driver differentiates between accessing Pipeline A
and B, specifically is the timeout being experienced due to the fact
that we didn't communicate to the proper pipeline's registers during a
BitBlt operation?
If there is anyone out there who has the fundamental understanding of
using these devices, your help would be greatly appreciated.
I know this is a shot in the dark, but why not.
Donald
xorg at kayser dot net
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