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From: Xin LI <delphij@FreeBSD.org>
Date: Wed, 9 Nov 2011 21:53:49 +0000 (UTC)
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Subject: svn commit: r227409 - head/sys/dev/mfi
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Author: delphij
Date: Wed Nov  9 21:53:49 2011
New Revision: 227409
URL: http://svn.freebsd.org/changeset/base/227409

Log:
  Do a dummy read to flush the interrupt ACK that we just performed,
  ensuring that everything is really, truly consistent.
  
  This fixes certain cases where one will see various:
  
  mfi0: COMMAND 0xffffffXXXXXXXXXX TIMEOUT AFTER XX SECONDS
  
  MFC after:	3 days
  Submitted by:	scottl
  Ok'ed by:	jhb

Modified:
  head/sys/dev/mfi/mfi.c

Modified: head/sys/dev/mfi/mfi.c
==============================================================================
--- head/sys/dev/mfi/mfi.c	Wed Nov  9 21:41:18 2011	(r227408)
+++ head/sys/dev/mfi/mfi.c	Wed Nov  9 21:53:49 2011	(r227409)
@@ -932,6 +932,12 @@ mfi_intr(void *arg)
 	if (sc->mfi_check_clear_intr(sc))
 		return;
 
+	/*
+	 * Do a dummy read to flush the interrupt ACK that we just performed,
+	 * ensuring that everything is really, truly consistent.
+	 */
+	(void)sc->mfi_read_fw_status(sc);
+
 	pi = sc->mfi_comms->hw_pi;
 	ci = sc->mfi_comms->hw_ci;
 	mtx_lock(&sc->mfi_io_lock);