[src/jdolecek-ncq]: src/sys/dev/ata actually change the retry to also use NCQ...

[jdolecek <jdolecek%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/6a57f508f7f2
branches:  jdolecek-ncq
changeset: 822982:6a57f508f7f2
user:      jdolecek <jdolecek%NetBSD.org@localhost>
date:      Sun Jul 30 20:16:29 2017 +0000

description:
actually change the retry to also use NCQ - with one drive I see
very frequent fatal errors on siisata when switching often between
NCQ and non-NCQ I/O commands with chaos monkey (basically, always
the next NCQ command on a slot which had non-NCQ I/O throws fatal
error); they completely vanish when just using NCQ all the time

diffstat:

 sys/dev/ata/wd.c |  16 +++++-----------
 1 files changed, 5 insertions(+), 11 deletions(-)

diffs (38 lines):

diff -r 414e1a72e8cc -r 6a57f508f7f2 sys/dev/ata/wd.c
--- a/sys/dev/ata/wd.c  Sat Jul 29 22:40:04 2017 +0000
+++ b/sys/dev/ata/wd.c  Sun Jul 30 20:16:29 2017 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: wd.c,v 1.428.2.30 2017/07/29 12:51:22 jdolecek Exp $ */
+/*     $NetBSD: wd.c,v 1.428.2.31 2017/07/30 20:16:29 jdolecek Exp $ */
 
 /*
  * Copyright (c) 1998, 2001 Manuel Bouyer.  All rights reserved.
@@ -54,7 +54,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: wd.c,v 1.428.2.30 2017/07/29 12:51:22 jdolecek Exp $");
+__KERNEL_RCSID(0, "$NetBSD: wd.c,v 1.428.2.31 2017/07/30 20:16:29 jdolecek Exp $");
 
 #include "opt_ata.h"
 #include "opt_wd.h"
@@ -734,16 +734,10 @@
                xfer->c_bio.flags |= ATA_LBA48;
 
        /*
-        * If NCQ was negotiated, always use it for the first attempt.
-        * Since device cancels all outstanding requests on error, downgrade
-        * to non-NCQ on retry, so that the retried transfer would not cause
-        * cascade failure for the other transfers if it fails again.
-        * If FUA was requested, we can't downgrade, as that would violate
-        * the semantics - FUA would not be honored. In that case, continue
-        * retrying with NCQ.
+        * If NCQ was negotiated, always use it. Some drives return random
+        * errors when switching between NCQ and non-NCQ I/O too often. 
         */
-       if (wd->drvp->drive_flags & ATA_DRIVE_NCQ &&
-           (xfer->c_retries == 0 || (bp->b_flags & B_MEDIA_FUA))) {
+       if (wd->drvp->drive_flags & ATA_DRIVE_NCQ) {
                xfer->c_bio.flags |= ATA_LBA48;
                xfer->c_flags |= C_NCQ;