Re: PCI latency and VGA drivers

[brians@Aureal.com (Brian Sassone)]

> look at the draft version of PC 99 (available from intel and microsoft web
> sites); there is a new item requiring max. 10us write latency for any PCI
> card.
> 
> This addresses the retry problem, which is not specific to VGA (but you
> will find it most often in that area).

Well, it certainly *tries* to address the problem.  If my device has to wait
to get the bus every 10us, I need a burst length of 50 DWORDS to maintain a
transfer rate of 20MB/s.  That adds up to a whole lot of FIFO memory for a
multi-channel real-time device.  And, that assumes long bursts are supported
by whatever chipset I am using.

Brian

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Brian Sassone (brians@aureal.com)                Aureal Semiconductor
HW Design Manager, PC Products Group             4245 Technology Drive
510-252-4225                                     Fremont, California 94538
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