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From: ggs@ulysses.homer.nj.att.com (Griff Smith)
Newsgroups: comp.bugs.4bsd
Subject: Spurious "done" interrupt after autoconfigure of TU78
Message-ID: <2786@ulysses.homer.nj.att.com>
Date: Tue, 11-Aug-87 16:26:04 EDT
Article-I.D.: ulysses.2786
Posted: Tue Aug 11 16:26:04 1987
Date-Received: Thu, 13-Aug-87 06:04:43 EDT
Organization: AT&T Bell Laboratories, Murray Hill
Lines: 36


Index:	/sys/vaxmba/mt.c 4.3BSD

Description:
	The autoconfigure code for the TU78 tape device driver sometimes
	causes an unsolicited "done" interrupt - harmless, but annoying.
Repeat-By:
	Try it on a processor faster than a VAX 11/785.
Fix:
	The following is my best guess - increasing the delay time seems
	to help:

*** /source/sys/vaxmba/mt.c	Thu Jun  5 04:32:57 1986
--- /sys/vaxmba/mt.c	Tue Aug 11 14:50:13 1987
***************
*** 154,160 ****
  	/* Cancel the interrupt, then wait a little while for it to go away. */
  
  	mtaddr->mtas = mtaddr->mtas;
! 	DELAY(10);
  	splx(s);
  	return (rtn);
  }
--- 155,161 ----
  	/* Cancel the interrupt, then wait a little while for it to go away. */
  
  	mtaddr->mtas = mtaddr->mtas;
! 	DELAY(100);
  	splx(s);
  	return (rtn);
  }
-- 
Griff Smith	AT&T (Bell Laboratories), Murray Hill
Phone:		1-201-582-7736
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