On Thursday 07 February 2002 12:37 pm, Jose Fonseca wrote:

> Their glossary (http://utah-glx.sourceforge.net/faq.html#AEN364) gives
> the definition of PIO, DMA and Pseudo DMA.

PsuedoDMA is pushing the command data in a DMA-able format to an engine that 
issues PIO commands one-by-one.  It's actually slower than doing PIO 
commands, but allows you to have one pathway for all conditions instead of 
two differing ways of sending commands to the chip, which makes for easier 
development in the blocks of code issuing the rendering commands.

On a different note, I had some things come up that kept me away from 
completing the initial cut of the Mach64 DMA code- I should be getting back 
on track over this weekend and should be building a sub-branch of the Mach64 
branch shortly.  It will NOT be secure (in the sense that ill-behaved code 
can't take a box out) for this revision while I work out the details of 
securing it.  Unlike the other chips, apparently there's no distinction 
between sets of commands such that I can say, "here's a set of verticies, go 
to it," to the chip, so I either have to come up with a PDMA-ish convention 
that will degrade performance or come up with some sort of watchdog process 
inside the module to detect a hang and reset the chip accordingly.  (My vote 
is for seeing if we can come up with a quick check for a locked up state and 
doing a reset as we now know how to do a full reset that resets the DMA, etc. 
on the chip from all of our hacking about to get the DMA test working.).

-- 
Frank Earl

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