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.

David
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