busmaster/latency for video

[Geert Uytterhoeven]

On Thu, 7 Oct 1999, Michel Lanners wrote:
> On   7 Oct, this message from Geert Uytterhoeven echoed through cyberspace:
> > On Thu, 7 Oct 1999, Michel Lanners wrote:
> >> On   6 Oct, this message from Ryan Nielsen echoed through cyberspace:
> >> > PCI_COMMAND_MASTER is not enabled and latency = 0 for the ultimate rez video card, and pci_write_config_*
> >> > do not change them. latency = 32 and mastering is enabled for all the other cards in the machine,
> >> > 
> >> > should they be enabled ?
> >> 
> >> That probably means the card doesn't support them.
> >> 
> >> Normal graphic cards have no need for mastership. Only those with video
> >> inputs need it, in order to transfer video data into the framebuffer
> >> without CPU help.
> > 
> > Many recent graphics chips to support bus mastering, especially the AGP ones.
> 
> 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...

I know my (non-Apple) OF warns me when I try to put a bus mastering-capable PCI
board in the right-most PCI slot (which doesn't support bus mastering).

Greetings,

						Geert

--
Geert Uytterhoeven ----------------- Sony Suprastructure Center Europe (SUPC-E)
Geert.Uytterhoeven at sonycom.com ------------------- Sint Stevens Woluwestraat 55
Phone +32-2-7248632 Fax +32-2-7262686 ---------------- B-1130 Brussels, Belgium


** Sent via the linuxppc-dev mail list. See http://lists.linuxppc.org/