2 files changed, 125 insertions, 60 deletions

diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c
index 1abfdba8d99b..31738627ec64 100644
--- a/drivers/ata/libata-eh.c
+++ b/drivers/ata/libata-eh.c
@@ -44,6 +44,12 @@
 
 #include "libata.h"
 
+enum {
+        ATA_EH_SPDN_NCQ_OFF             = (1 << 0),
+        ATA_EH_SPDN_SPEED_DOWN          = (1 << 1),
+        ATA_EH_SPDN_FALLBACK_TO_PIO     = (1 << 2),
+};
+
 static void __ata_port_freeze(struct ata_port *ap);
 static void ata_eh_finish(struct ata_port *ap);
 static void ata_eh_handle_port_suspend(struct ata_port *ap);
@@ -65,12 +71,9 @@ static void ata_ering_record(struct ata_ering *ering, int is_io,
         ent->timestamp = get_jiffies_64();
 }
 
-static struct ata_ering_entry * ata_ering_top(struct ata_ering *ering)
+static void ata_ering_clear(struct ata_ering *ering)
 {
-        struct ata_ering_entry *ent = &ering->ring[ering->cursor];
-        if (!ent->err_mask)
-                return NULL;
-        return ent;
+        memset(ering, 0, sizeof(*ering));
 }
 
 static int ata_ering_map(struct ata_ering *ering,
@@ -1159,87 +1162,99 @@ static unsigned int ata_eh_analyze_tf(struct ata_queued_cmd *qc,
         return action;
 }
 
-static int ata_eh_categorize_ering_entry(struct ata_ering_entry *ent)
+static int ata_eh_categorize_error(int is_io, unsigned int err_mask)
 {
-        if (ent->err_mask & (AC_ERR_ATA_BUS | AC_ERR_TIMEOUT))
+        if (err_mask & AC_ERR_ATA_BUS)
                 return 1;
 
-        if (ent->is_io) {
-                if (ent->err_mask & AC_ERR_HSM)
-                        return 1;
-                if ((ent->err_mask &
-                     (AC_ERR_DEV|AC_ERR_MEDIA|AC_ERR_INVALID)) == AC_ERR_DEV)
+        if (err_mask & AC_ERR_TIMEOUT)
+                return 2;
+
+        if (is_io) {
+                if (err_mask & AC_ERR_HSM)
                         return 2;
+                if ((err_mask &
+                     (AC_ERR_DEV|AC_ERR_MEDIA|AC_ERR_INVALID)) == AC_ERR_DEV)
+                        return 3;
         }
 
         return 0;
 }
 
-struct speed_down_needed_arg {
+struct speed_down_verdict_arg {
         u64 since;
-        int nr_errors[3];
+        int nr_errors[4];
 };
 
-static int speed_down_needed_cb(struct ata_ering_entry *ent, void *void_arg)
+static int speed_down_verdict_cb(struct ata_ering_entry *ent, void *void_arg)
 {
-        struct speed_down_needed_arg *arg = void_arg;
+        struct speed_down_verdict_arg *arg = void_arg;
+        int cat = ata_eh_categorize_error(ent->is_io, ent->err_mask);
 
         if (ent->timestamp < arg->since)
                 return -1;
 
-        arg->nr_errors[ata_eh_categorize_ering_entry(ent)]++;
+        arg->nr_errors[cat]++;
         return 0;
 }
 
 /**
- *      ata_eh_speed_down_needed - Determine wheter speed down is necessary
+ *      ata_eh_speed_down_verdict - Determine speed down verdict
  *      @dev: Device of interest
  *
  *      This function examines error ring of @dev and determines
- *      whether speed down is necessary.  Speed down is necessary if
- *      there have been more than 3 of Cat-1 errors or 10 of Cat-2
- *      errors during last 15 minutes.
+ *      whether NCQ needs to be turned off, transfer speed should be
+ *      stepped down, or falling back to PIO is necessary.
+ *
+ *      Cat-1 is ATA_BUS error for any command.
  *
- *      Cat-1 errors are ATA_BUS, TIMEOUT for any command and HSM
- *      violation for known supported commands.
+ *      Cat-2 is TIMEOUT for any command or HSM violation for known
+ *      supported commands.
  *
- *      Cat-2 errors are unclassified DEV error for known supported
+ *      Cat-3 is is unclassified DEV error for known supported
  *      command.
  *
+ *      NCQ needs to be turned off if there have been more than 3
+ *      Cat-2 + Cat-3 errors during last 10 minutes.
+ *
+ *      Speed down is necessary if there have been more than 3 Cat-1 +
+ *      Cat-2 errors or 10 Cat-3 errors during last 10 minutes.
+ *
+ *      Falling back to PIO mode is necessary if there have been more
+ *      than 10 Cat-1 + Cat-2 + Cat-3 errors during last 5 minutes.
+ *
  *      LOCKING:
  *      Inherited from caller.
  *
  *      RETURNS:
- *      1 if speed down is necessary, 0 otherwise
+ *      OR of ATA_EH_SPDN_* flags.
  */
-static int ata_eh_speed_down_needed(struct ata_device *dev)
+static unsigned int ata_eh_speed_down_verdict(struct ata_device *dev)
 {
-        const u64 interval = 15LLU * 60 * HZ;
-        static const int err_limits[3] = { -1, 3, 10 };
-        struct speed_down_needed_arg arg;
-        struct ata_ering_entry *ent;
-        int err_cat;
-        u64 j64;
+        const u64 j5mins = 5LLU * 60 * HZ, j10mins = 10LLU * 60 * HZ;
+        u64 j64 = get_jiffies_64();
+        struct speed_down_verdict_arg arg;
+        unsigned int verdict = 0;
 
-        ent = ata_ering_top(&dev->ering);
-        if (!ent)
-                return 0;
+        /* scan past 10 mins of error history */
+        memset(&arg, 0, sizeof(arg));
+        arg.since = j64 - min(j64, j10mins);
+        ata_ering_map(&dev->ering, speed_down_verdict_cb, &arg);
 
-        err_cat = ata_eh_categorize_ering_entry(ent);
-        if (err_cat == 0)
-                return 0;
+        if (arg.nr_errors[2] + arg.nr_errors[3] > 3)
+                verdict |= ATA_EH_SPDN_NCQ_OFF;
+        if (arg.nr_errors[1] + arg.nr_errors[2] > 3 || arg.nr_errors[3] > 10)
+                verdict |= ATA_EH_SPDN_SPEED_DOWN;
 
+        /* scan past 3 mins of error history */
         memset(&arg, 0, sizeof(arg));
+        arg.since = j64 - min(j64, j5mins);
+        ata_ering_map(&dev->ering, speed_down_verdict_cb, &arg);
 
-        j64 = get_jiffies_64();
-        if (j64 >= interval)
-                arg.since = j64 - interval;
-        else
-                arg.since = 0;
-
-        ata_ering_map(&dev->ering, speed_down_needed_cb, &arg);
+        if (arg.nr_errors[1] + arg.nr_errors[2] + arg.nr_errors[3] > 10)
+                verdict |= ATA_EH_SPDN_FALLBACK_TO_PIO;
 
-        return arg.nr_errors[err_cat] > err_limits[err_cat];
+        return verdict;
 }
 
 /**
@@ -1257,31 +1272,80 @@ static int ata_eh_speed_down_needed(struct ata_device *dev)
  *      Kernel thread context (may sleep).
  *
  *      RETURNS:
- *      0 on success, -errno otherwise
+ *      Determined recovery action.
  */
-static int ata_eh_speed_down(struct ata_device *dev, int is_io,
-                             unsigned int err_mask)
+static unsigned int ata_eh_speed_down(struct ata_device *dev, int is_io,
+                                      unsigned int err_mask)
 {
-        if (!err_mask)
+        unsigned int verdict;
+        unsigned int action = 0;
+
+        /* don't bother if Cat-0 error */
+        if (ata_eh_categorize_error(is_io, err_mask) == 0)
                 return 0;
 
         /* record error and determine whether speed down is necessary */
         ata_ering_record(&dev->ering, is_io, err_mask);
+        verdict = ata_eh_speed_down_verdict(dev);
 
-        if (!ata_eh_speed_down_needed(dev))
-                return 0;
+        /* turn off NCQ? */
+        if ((verdict & ATA_EH_SPDN_NCQ_OFF) &&
+            (dev->flags & (ATA_DFLAG_PIO | ATA_DFLAG_NCQ |
+                           ATA_DFLAG_NCQ_OFF)) == ATA_DFLAG_NCQ) {
+                dev->flags |= ATA_DFLAG_NCQ_OFF;
+                ata_dev_printk(dev, KERN_WARNING,
+                               "NCQ disabled due to excessive errors\n");
+                goto done;
+        }
+
+        /* speed down? */
+        if (verdict & ATA_EH_SPDN_SPEED_DOWN) {
+                /* speed down SATA link speed if possible */
+                if (sata_down_spd_limit(dev->ap) == 0) {
+                        action |= ATA_EH_HARDRESET;
+                        goto done;
+                }
 
-        /* speed down SATA link speed if possible */
-        if (sata_down_spd_limit(dev->ap) == 0)
-                return ATA_EH_HARDRESET;
+                /* lower transfer mode */
+                if (dev->spdn_cnt < 2) {
+                        static const int dma_dnxfer_sel[] =
+                                { ATA_DNXFER_DMA, ATA_DNXFER_40C };
+                        static const int pio_dnxfer_sel[] =
+                                { ATA_DNXFER_PIO, ATA_DNXFER_FORCE_PIO0 };
+                        int sel;
 
-        /* lower transfer mode */
-        if (ata_down_xfermask_limit(dev, ATA_DNXFER_ANY) == 0)
-                return ATA_EH_SOFTRESET;
+                        if (dev->xfer_shift != ATA_SHIFT_PIO)
+                                sel = dma_dnxfer_sel[dev->spdn_cnt];
+                        else
+                                sel = pio_dnxfer_sel[dev->spdn_cnt];
+
+                        dev->spdn_cnt++;
+
+                        if (ata_down_xfermask_limit(dev, sel) == 0) {
+                                action |= ATA_EH_SOFTRESET;
+                                goto done;
+                        }
+                }
+        }
+
+        /* Fall back to PIO?  Slowing down to PIO is meaningless for
+         * SATA.  Consider it only for PATA.
+         */
+        if ((verdict & ATA_EH_SPDN_FALLBACK_TO_PIO) && (dev->spdn_cnt >= 2) &&
+            (dev->ap->cbl != ATA_CBL_SATA) &&
+            (dev->xfer_shift != ATA_SHIFT_PIO)) {
+                if (ata_down_xfermask_limit(dev, ATA_DNXFER_FORCE_PIO) == 0) {
+                        dev->spdn_cnt = 0;
+                        action |= ATA_EH_SOFTRESET;
+                        goto done;
+                }
+        }
 
-        ata_dev_printk(dev, KERN_ERR,
-                       "speed down requested but no transfer mode left\n");
         return 0;
+ done:
+        /* device has been slowed down, blow error history */
+        ata_ering_clear(&dev->ering);
+        return action;
 }
 
 /**
diff --git a/include/linux/libata.h b/include/linux/libata.h
index 60dfc5f7e882..5db50fa594ac 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -495,6 +495,7 @@ struct ata_device {
 
         /* error history */
         struct ata_ering        ering;
+        int                     spdn_cnt;
         unsigned int            horkage;        /* List of broken features */
 #ifdef CONFIG_SATA_ACPI
         /* ACPI objects info */