Re: parport-arca-9 [was Re: [PARPORT] Re: PARPORT_DEV_EXCL ]

Andrea Arcangeli (
Sat, 26 Sep 1998 21:05:41 +0200 (CEST)

On Sat, 26 Sep 1998, Philip Blundell wrote:

>It's perfectly allowable for the preempt function to always fail (though it
>ought to be OK to simply provide no preempt function in this case -- the only
>reason the drivers in question had one is because lurkers were supposed to
>always be preemptable back when that flag had a meaning).

Woops now I understand why there was such ~null preempt function ;-).

>The only restriction is that if your driver isn't preemptable you have to be
>sure that it will release the port of its own accord within a finite
>timeframe. For example, the QuickCam driver isn't preemptable but it only

As ppa does.

>claims the port while a frame is actually being captured. You only need the
>EXCL flag for devices where this isn't the case.

I catched this case right reading the qcam code infact.

Andrea[s] Arcangeli

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This archive was generated by hypermail 2.0b3 on Wed 30 Dec 1998 - 10:18:25 EST