Re: busmaster/latency for video

[Michel Lanners <mlan@cpu.lu>]

On   8 Oct, this message from Benjamin Herrenschmidt echoed through cyberspace:
> On Thu, Oct 7, 1999, Michel Lanners <mlan@cpu.lu> wrote:
> 
>>Ah, but in that case Apple's OF should enable bus mastering. If I read
>>well between the lines of Apple's docs, OF should set a few default
>>parameters on all PCI devices, among which bus mastering. I'm not sure
>>about latency, though...
> 
> OF tends to ignore devices that don't have an OF expansion ROM. (For
> example, it won't enable memory or IO accesses in the command register).
> I beleive it won't enable bus mastering neither but I may be wrong.

OF itself doesn't enable any memory or IO region; it's the
device-specific init code (which might be on-board for PCI cards, or in
OF for motherboard devices).

There are, however, a few things OF does for _every_ PCI device, among
which enabling bus mastering and assigning memory and/or IO resources.

Michel

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