On Tue, 3 Dec 2002, David Brownell wrote:
>> a driver is supposed to abort URBs after a device is disconnected?
>
>It's supposed to do that in disconnect(), yes, for any
>urbs that haven't yet completed. In what way would it
>be possible to achieve #1 without #2 ??
I was under the impression that the HCD would notice (during the next
frame) that those TDs (or EDs) have a target device that's no longer
connected, and finish them with an error. If not, then how can the
host controller execute that TD/ED? The device isn't there...
But if the driver does need to remove its URBs from the HCD, then
you're right - disconnect() should be all that's needed (AFAIK) except
for device state.
>You (and Oliver) seem to be assuming that disconnect() is
>about hardware. It's not. It's about driver unbinding.
>The unbinding does happen when hardware goes away, but
>it also happens at other times (driver rmmod, etc).
yep. Remember way back when I suggested, instead of a forcible
disconnect, a driver ioctl (that had to be implemented by all drivers)
to disconnect 'nicely'? That would have let the driver finish
whatever it was doing and fixup the device state...ah well...
>> I thought those URBs would be completed with error (ENODEV or ECONNRESET).
>
>That's what happens when the driver unlinks them (synchronously or
>asynchronously, respectively).
well ('cept for device state) we're cool then, eh? ;)
>The reason _why_ a driver releases an interface doesn't
>change the semantics of releasing it. Releasing involves
>your point #1 (which implies #2).
It just seems strange to me to be aborting URBs for a device that no
longer exists...seems like the HCD would just clean them out during
the next frame. Especially since it would be easier (more
centralized) to do it in the HCD, while doing it in the drivers is
more work...
--
Dan Streetman
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