On Thu, Oct 17, 2002 at 11:17:39AM -0600, Marc Aurele La France wrote:
> On 17 Oct 2002, Michel Dänzer wrote:
> 
> > On Don, 2002-10-17 at 04:50, David Dawes wrote:
> > > On Tue, Oct 15, 2002 at 12:28:27AM +0200, Charl P. Botha wrote:
> > > >On Mon, Oct 14, 2002 at 04:14:22PM -0600, Marc Aurele La France wrote:
> > > >> On Tue, 15 Oct 2002, Charl P. Botha wrote:
> > > >> > This would mean that the bug is back and people will again have the stupid
> 
> > > >> No, it doesn't.
> 
> > > >> > VT switch lockup.  What would be the New and Improved Way(tm) way of
> > > >> > explicitly re-enabling bus-mastering at RADEONEnterVT() time since
> > > >> > xf86EnablePciBusMaster() has been deprecated?
> 
> > > >> Just like the change notice says:  When a PCI device is enabled, it's bus
> > > >> mastering is also enabled.  This occurs before any driver code is
> > > >> executed.
> 
> > > >I'm running the DRI tree, so I can't test.  However, we still don't know why
> > > >these cards disabled bus mastering at VT switches (when it was very clearly
> > > >enabled before the switch), so what guarantees that they won't still do
> > > >this?  Mike (Harris), do you have one of the affected cards running XFree86
> > > >HEAD?
> 
> > > No, the X server restores changes is makes to the PCI state when it
> > > gives up control of the console, so if bus mastering wasn't enabled
> > > *before* the X server started, it won't be after VT switching away.
> > > Several drivers had bugs where they didn't re-enable it when switching
> > > back.  Drivers shouldn't assume anything more about the HW state after
> > > returning from a VT switch than they would at startup, but unfortunately
> > > some still do...
> 
> > > Marc's change means that drivers don't need to care about bus mastering
> > > being enabled because it will now be enabled automatically for PCI cards
> > > that are being used by the X server.
> 
> > Sounds good, unfortunately it doesn't seem to work for the original
> > poster - any idea why?
> 
> Charl P. Botha did not actually try it.  Thus, the key word in your
> sentence above remains "seem".

Sorry for the long quote above, but this should be almost the last mail in
this thread.  I've tested with CVS XFree86, and all is well.  Bus mastering
gets disabled when switched to VT but gets enabled again when switching back
to X.

The problem WAS that this re-enabling did not always take place before
Marc's changes, which is why we added the explicit call to do this.  I've
checked the code in current XFree86 CVS, but would very much like to know
(just for interest's sake) WHERE exactly the PCI enable (or whatnot) is
called from that re-enables bus mastering after a VT switch.

Thanks and my apologies for the upset.

-- 
charl p. botha http://cpbotha.net/ http://visualisation.tudelft.nl/


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