[src/trunk]: src/sys/dev/ata disable downgrade of ATA mode from DMA, as gener...

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

details:   https://anonhg.NetBSD.org/src/rev/805fee4dfed8
branches:  trunk
changeset: 933487:805fee4dfed8
user:      jdolecek <jdolecek%NetBSD.org@localhost>
date:      Mon May 25 19:05:30 2020 +0000

description:
disable downgrade of ATA mode from DMA, as generally not relevant
any more - while it has been instrumental to inadvertedly discover
driver bugs in PIO mode under QEMU recently, generally the switch
more hurts than helps, so now only warn when DMA errors happen

code kept under ATA_DOWNGRADE_MODE ifdef, disabled by default

diffstat:

 sys/dev/ata/ata.c |  21 ++++++++++++++++-----
 1 files changed, 16 insertions(+), 5 deletions(-)

diffs (65 lines):

diff -r 70deec445bc5 -r 805fee4dfed8 sys/dev/ata/ata.c
--- a/sys/dev/ata/ata.c Mon May 25 19:01:15 2020 +0000
+++ b/sys/dev/ata/ata.c Mon May 25 19:05:30 2020 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: ata.c,v 1.158 2020/05/25 18:29:25 jdolecek Exp $       */
+/*     $NetBSD: ata.c,v 1.159 2020/05/25 19:05:30 jdolecek Exp $       */
 
 /*
  * Copyright (c) 1998, 2001 Manuel Bouyer.  All rights reserved.
@@ -25,7 +25,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: ata.c,v 1.158 2020/05/25 18:29:25 jdolecek Exp $");
+__KERNEL_RCSID(0, "$NetBSD: ata.c,v 1.159 2020/05/25 19:05:30 jdolecek Exp $");
 
 #include "opt_ata.h"
 
@@ -84,7 +84,7 @@
 #define ATADEBUG_PRINT(args, level)
 #endif
 
-#if NATA_DMA
+#if defined(ATA_DOWNGRADE_MODE) && NATA_DMA
 static int     ata_downgrade_mode(struct ata_drive_datas *, int);
 #endif
 
@@ -965,8 +965,19 @@
         */
        drvp->n_dmaerrs++;
        if (drvp->n_dmaerrs >= NERRS_MAX && drvp->n_xfers <= NXFER) {
+#ifdef ATA_DOWNGRADE_MODE
                ata_downgrade_mode(drvp, flags);
                drvp->n_dmaerrs = NERRS_MAX-1;
+#else
+               static struct timeval last;
+               static const struct timeval serrintvl = { 300, 0 };
+
+               if (ratecheck(&last, &serrintvl)) {
+                       aprint_error_dev(drvp->drv_softc,
+                           "excessive DMA errors - %d in last %d transfers\n",
+                           drvp->n_dmaerrs, drvp->n_xfers);
+               }
+#endif
                drvp->n_xfers = 0;
                return;
        }
@@ -1752,7 +1763,7 @@
        }
 }
 
-#if NATA_DMA
+#if defined(ATA_DOWNGRADE_MODE) && NATA_DMA
 /*
  * downgrade the transfer mode of a drive after an error. return 1 if
  * downgrade was possible, 0 otherwise.
@@ -1809,7 +1820,7 @@
        ata_thread_run(chp, flags, ATACH_TH_RESET, ATACH_NODRIVE);
        return 1;
 }
-#endif /* NATA_DMA */
+#endif /* ATA_DOWNGRADE_MODE && NATA_DMA */
 
 /*
  * Probe drive's capabilities, for use by the controller later