[6126] in linux-scsi channel archive
Re: Guru required: BUSY status
daemon@ATHENA.MIT.EDU (Marc SCHAEFER)
Fri Mar 19 01:59:50 1999
Date: Fri, 19 Mar 1999 07:49:37 +0100 (MET)
From: Marc SCHAEFER <schaefer@alphanet.ch>
To: grant@torque.net
cc: linux-scsi@vger.rutgers.edu
In-Reply-To: <199903182242.RAA24473@knot.torque.net>
On Thu, 18 Mar 1999 grant@torque.net wrote:
> The standard says: "The reselected initiator shall then assert the BSY signal
> within a _selection_abort_time_ of its most recent detection ..."
Well, the standard also says:
4.7.16 Selection Abort Time
The maximum time that a target (or initiator) shall take from its most
recent detection of being selected (or reselected) until asserting a
BSY response. This time-out is required to ensure that a target (or
initiator) does not assert BSY after a SELECTION (or RESELECTION) phase
has been aborted.
This is not the selection time-out period; see 5.1.3.1 and 5.1.4.2 for
a complete description.
4.7.17 Selection Time-out Delay [ 250 ms recommended ]
The minimum time that a SCSI device should wait for a BSY response
during the SELECTION or RESELECTION phase before starting the time-out
procedure. Note that this is only a recommended time period.
And:
5.1.4.2 RESELECTION Time-out Procedure
Two optional RESELECTION time-out procedures are specified for clearing
the SCSI bus during a RESELECTION phase if the target waits a minimum
of a selection time-out delay and there has been no BSY signal response
from the initiator:
Basically, a RESELECTION is a SELECTION with the I/O signal asserted.
The selection abort time is just there to ensure that the initiator
doesn't falsely answer to a selection. Basically, as soon as you
DETECTED you are reselected you MUST assert the BUSY signal before
the selection abort time. So this must be done in the same interrupt
routine.
> I'll look at that - but are you sure that the eh logic won't reset the
> bus ?
It didn't two years ago :)
-
To unsubscribe from this list: send the line "unsubscribe linux-scsi" in
the body of a message to majordomo@vger.rutgers.edu
