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Date:      Fri, 15 Aug 2003 01:55:34 -0700
From:      Terry Lambert <tlambert2@mindspring.com>
To:        "M. Warner Losh" <imp@bsdimp.com>
Cc:        freebsd-current@freebsd.org
Subject:   Re: usbd does not use detach
Message-ID:  <3F3CA006.34B78D8D@mindspring.com>
References:  <1060185309.676.1.camel@Twoflower.liebende.de> <1060504397.777.15.camel@syrenna.deep-ocean.local> <20030814.223735.103163505.imp@bsdimp.com>

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"M. Warner Losh" wrote:
> These two are redundant.  Devices can already ask the bridge driver if
> the device is still present on the bus.  Smart drivers already do
> this, but most of the drivers in the tree are dumb.  You also have to
> deal with device disappearance in ISRs since it is possible for the
> device to go away while the device is in the middle of the ISR.  Some
> bus technologies also allow interrupt entry when a card/device is
> ejected.

Another common case is to hibernate/sleep/suspend/whatever the
machine, and then disconnect the device out from under it, and
it not being there when the machine wakes back up.  Almost all
MP3 players and Palm devices have that issues (since the order
of human operation is to shut off the machine, get the wallet
and keys, grab the iPod (or whatever), and head out the door).

-- Terry



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