Re: [linux-usb-devel] Re: [PATCH] USB changes for 2.5.58

[David Brownell <david-b@pacbell.net>]

Oliver Neukum wrote:
> I should be more specific.

Yes...


> The SCSI is different for several reasons:
> - we are talking about bus as well as device detection
> - there's no common way to probe for devices
>   (the probing of LUNs works only on conventional busses)

So the SCSI stack needs to support more than one model for
device/bus detection.  This can't be news.  And some of them
have to handle "conventional" busses, like USB and PCI; maybe
even handle booting off them...


> - many SCSI devices are not really SCSI devices. They just use
>   the command set
> 
> SCSI hotplug detection doesn't work for the same reason that USB
> can handle only detection of devices by itself. Busses on the other
> hand are not handled by USB itself.

Just how is it that USB doesn't handle USB?  "B" == "Bus" ... :)

If you mean that HCs hook up to a different bus (often PCI), with its
own hotplug support, that doesn't seem so different from SCSI HBAs
hooking up to such busses (often PCI) and cascading the same hotplug
support...


>>Erm ... which of the three SCSI layers are you talking about?  I was
>>talking about the highest level,..
> 
> 
> In SCSI view device and bus disconnection is recognised by the lowest
> level. As it knows nothing about the high layers, it notifies the midlayer

So you were talking past what I said about notifying that highest level,
not disagreeing with it.