Re: Please revert 5adc55da4a7758021bcc374904b0f8b076508a11 (PCI_MULTITHREAD_PROBE)

[Stefan Richter <stefanr@s5r6.in-berlin.de>]

Cornelia Huck wrote:
> On Wed, 9 May 2007 01:33:14 -0700 (PDT),
> david@lang.hm wrote:
> 
>> 1. why should different, unrelated busses need to wait for each other? 
>> picking two, why can't you have SCSI and USB going through their timeouts 
>> at the same time?
> 
> If they don't have dependencies on each other, yes. Some busses should
> be finished before probing for others start (e.g. low-level busses).

If there are dependencies, then a driver on the lower-level bus simply
hot-inserts a bus to the higher-level bus's driver when the lower-level
probe is done.

E.g. PCI or CardBus detects insertion of a IEEE 1394 controller,
ohci1394 adds a new IEEE 1394 bus to ieee1394 core, ieee1394core
discovers e.g. storage devices on this bus and kicks off sbp2's probe,
sbp2 adds them to SCSI core, SCSI core does the inquiry and kicks off a
SCSI command set driver's probe.  Meanwhile, userspace just waits for a
certain SCSI device to appear.  (And userspace inserts drivers according
to uevents a.k.a. hotplug events if the drivers weren't statically linked.)
-- 
Stefan Richter
-=====-=-=== -=-= -=--=
http://arcgraph.de/sr/