libata: Ignore spurious PHY event on LPM policy change

When the LPM policy is set to ATA_LPM_MAX_POWER, the device might
generate a spurious PHY event that cuases errors on the link.
Ignore this event if it occured within 10s after the policy change.

The timeout was chosen observing that on a Dell XPS13 9333 these
spurious events can occur up to roughly 6s after the policy change.

Link: http://lkml.kernel.org/g/3352987.ugV1Ipy7Z5@xps13
Signed-off-by: Gabriele Mazzotta <gabriele.mzt@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: stable@vger.kernel.org

2 files changed, 17 insertions, 1 deletions

diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 12adcf78f94b..85e659945c12 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -6766,8 +6766,21 @@ u32 ata_wait_register(struct ata_port *ap, void __iomem *reg, u32 mask, u32 val,
  */
 bool sata_lpm_ignore_phy_events(struct ata_link *link)
 {
+        unsigned long lpm_timeout = link->last_lpm_change +
+                                    msecs_to_jiffies(ATA_TMOUT_SPURIOUS_PHY);
+
         /* if LPM is enabled, PHYRDY doesn't mean anything */
-        return !!(link->lpm_policy > ATA_LPM_MAX_POWER);
+        if (link->lpm_policy > ATA_LPM_MAX_POWER)
+                return true;
+
+        /* ignore the first PHY event after the LPM policy changed
+         * as it is might be spurious
+         */
+        if ((link->flags & ATA_LFLAG_CHANGED) &&
+            time_before(jiffies, lpm_timeout))
+                return true;
+
+        return false;
 }
 EXPORT_SYMBOL_GPL(sata_lpm_ignore_phy_events);
 
diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c
index 07f41be38fbe..cf0022ec07f2 100644
--- a/drivers/ata/libata-eh.c
+++ b/drivers/ata/libata-eh.c
@@ -3597,6 +3597,9 @@ static int ata_eh_set_lpm(struct ata_link *link, enum ata_lpm_policy policy,
                 }
         }
 
+        link->last_lpm_change = jiffies;
+        link->flags |= ATA_LFLAG_CHANGED;
+
         return 0;
 
 fail: