[4029] in linux-scsi channel archive
Re: SCSI Timeout on AIC7xxx when PPA is active.
daemon@ATHENA.MIT.EDU (Mark Garlanger)
Thu May 28 21:24:32 1998
Date: Thu, 28 May 1998 20:16:59 -0500
From: Mark Garlanger <garlangr@cyberramp.net>
To: David Campbell <campbell@gear.torque.net>
CC: linux-scsi@vger.rutgers.edu
David Campbell wrote:
> > Date: Thu, 28 May 1998 06:59:03 -0500
> > From: Mark Garlanger <garlangr@cyberramp.net>
> > To: David Campbell <campbell@gear.torque.net>
> > Cc: linux-parport@torque.net, linux-scsi@vger.rutgers.edu
> > Subject: Re: SCSI Timeout on AIC7xxx when PPA is active.
>
> *snip*
>
> > 1) Zip drive unplugged but driver still in the kernel
>
> *snip*
> SMP => OK
> !SMP => OK (??)
Since SMP worked, I felt !SMP would work without issue...
>
>
> > 2) Zip drive plugged in, turned on but no disk in drive
>
> *snip*
> SMP => Crash
> !SMP => ????
Tried the !SMP a few minutes ago, it crashes too.
>
>
> > 3) Zip drive plugged in, turned on but with a disk in drive
>
> *snip*
> SMP => Crash
> !SMP => ????
!SMP also crashes..
>
>
> *light bulb over head*
>
> The problem may reside in the the AIC7xxx driver. When *any* low level
> driver completes a command then the mid-level driver checks *all* low
> level drivers to see if they can accept another command.
>
> Perhaps when ppa returns from a command it sees that the AIC7xxx is free
> (incorrectly) and sends it a SCSI command which jams the queue (this
> would fit the symptoms).
>
> Another posibility is that ppa calls the completion function in an
> interrupt (OK - software interrupt. tq_timer to be exact). The AIC7xxx may
> receive its next instruction in this state and do something strange with
> it.
Would it be possible to move this function completion call to outside the
interruptin order to test this out.
Thanks,
Mark
>
>
> I will take a quick peek at the AIC code, don't expect any miracles.
>
> David Campbell
> =======================================================
> campbell@torque.net
>
> "All parallel ports are equal - Some are more equal than others"
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