1 files changed, 38 insertions, 0 deletions

diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c
index 685509bc7ff0..caa1e9fde3c9 100644
--- a/drivers/ata/libata-eh.c
+++ b/drivers/ata/libata-eh.c
@@ -82,6 +82,10 @@ enum {
         ATA_EH_FASTDRAIN_INTERVAL       =  3000,
 
         ATA_EH_UA_TRIES                 = 5,
+
+        /* probe speed down parameters, see ata_eh_schedule_probe() */
+        ATA_EH_PROBE_TRIAL_INTERVAL     = 60000,        /* 1 min */
+        ATA_EH_PROBE_TRIALS             = 2,
 };
 
 /* The following table determines how we sequence resets.  Each entry
@@ -2975,9 +2979,24 @@ static int ata_eh_skip_recovery(struct ata_link *link)
         return 1;
 }
 
+static int ata_count_probe_trials_cb(struct ata_ering_entry *ent, void *void_arg)
+{
+        u64 interval = msecs_to_jiffies(ATA_EH_PROBE_TRIAL_INTERVAL);
+        u64 now = get_jiffies_64();
+        int *trials = void_arg;
+
+        if (ent->timestamp < now - min(now, interval))
+                return -1;
+
+        (*trials)++;
+        return 0;
+}
+
 static int ata_eh_schedule_probe(struct ata_device *dev)
 {
         struct ata_eh_context *ehc = &dev->link->eh_context;
+        struct ata_link *link = ata_dev_phys_link(dev);
+        int trials = 0;
 
         if (!(ehc->i.probe_mask & (1 << dev->devno)) ||
             (ehc->did_probe_mask & (1 << dev->devno)))
@@ -2990,6 +3009,25 @@ static int ata_eh_schedule_probe(struct ata_device *dev)
         ehc->saved_xfer_mode[dev->devno] = 0;
         ehc->saved_ncq_enabled &= ~(1 << dev->devno);
 
+        /* Record and count probe trials on the ering.  The specific
+         * error mask used is irrelevant.  Because a successful device
+         * detection clears the ering, this count accumulates only if
+         * there are consecutive failed probes.
+         *
+         * If the count is equal to or higher than ATA_EH_PROBE_TRIALS
+         * in the last ATA_EH_PROBE_TRIAL_INTERVAL, link speed is
+         * forced to 1.5Gbps.
+         *
+         * This is to work around cases where failed link speed
+         * negotiation results in device misdetection leading to
+         * infinite DEVXCHG or PHRDY CHG events.
+         */
+        ata_ering_record(&dev->ering, 0, AC_ERR_OTHER);
+        ata_ering_map(&dev->ering, ata_count_probe_trials_cb, &trials);
+
+        if (trials > ATA_EH_PROBE_TRIALS)
+                sata_down_spd_limit(link, 1);
+
         return 1;
 }