From 2fdfc7c6dcb209deb801c6cef1e057580051dfa4 Mon Sep 17 00:00:00 2001
From: Tejun Heo <tj@kernel.org>
Date: Thu, 29 Jan 2009 20:31:34 +0900
Subject: [PATCH] --- yaml --- r: 130815 b: refs/heads/master c:
 c2c7a89c5eabaea8c0c2aa0c1069e510144513ab h: refs/heads/master i:   130813:
 83e4d2e77251ae4876f89ff009a9c0fd8627cc42   130811:
 f6cee8138986f164aaa0b7557cc7376362fb40d9   130807:
 2b71bb00730aa560f0e6100ce91e0f758a94e63e   130799:
 684f09ea419bfc58197a05e136209de717ef40b6   130783:
 719f019bd5af7a857c21d1c331edd8df8e13b5c7   130751:
 4b63be376ff55b52dfd057f20708b3ec0312be9c   130687:
 b1ab60a419ef903cb782bb8109798127f7e7d808   130559:
 8813e85455b51189188fd60e81270afea0483bca v: v3

---
 [refs]                        |  2 +-
 trunk/drivers/ata/libata-eh.c | 38 +++++++++++++++++++++++++++++++++++
 2 files changed, 39 insertions(+), 1 deletion(-)

diff --git a/[refs] b/[refs]
index ea249b49e6e1..65d61dcaed5e 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: a07d499b4759881db1359dd8812eecd00b0e0a28
+refs/heads/master: c2c7a89c5eabaea8c0c2aa0c1069e510144513ab
diff --git a/trunk/drivers/ata/libata-eh.c b/trunk/drivers/ata/libata-eh.c
index 685509bc7ff0..caa1e9fde3c9 100644
--- a/trunk/drivers/ata/libata-eh.c
+++ b/trunk/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;
 }