Messages in this thread | | | Date | Tue, 7 Jan 2003 09:44:53 -0800 (PST) | From | Linus Torvalds <> | Subject | Re: [patch 2.5] PCI: allow alternative methods for probing the BARs |
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On 7 Jan 2003, Alan Cox wrote: > > On Tue, 2003-01-07 at 00:13, Grant Grundler wrote: > > On Mon, Jan 06, 2003 at 03:19:09PM -0800, Linus Torvalds wrote: > > > In particular, we can make the first phase disable DMA on the devices we > > > find, which means that we know they won't be generating PCI traffic during > > > the second phase - so now the second phase (which does the BAR sizing) can > > > do sizing and be safe in the knowledge that there should be no random PCI > > > activity ongoing at the same time. > > > > Did you expect the PCI_COMMAND_MASTER disabled in the USB Controller > > or something else in the controller turned off? > > There is another problem too. Some devices ignore the master bit disable. > VIA 8233/8235 being a fine example.
Well, I was actually thinking of really _stopping_ the USB controller and disable DMA that way. That's easy to do with a few trivial fixups - one for each USB controller type (and there are only three).
Because of legacy USB handling by the SMM BIOS, USB really ends up being a special case. There may be other special cases, of course, but the whole point of the fixups is exactly to handle special cases.
Linus
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