libata: issue DIPM enable commands with LPM state updated

Low level drivers may behave differently depending on the current
link->lpm_policy.  During ata_eh_set_lpm(), DIPM enable commands are
issued after the successful completion of ap->ops->set_lpm(), which
means that the controller is already in the target state.  This causes
DIPM enable commands to be processed with mismatching controller power
state and link->lpm_policy value.

In ahci, link->lpm_policy is used to ignore certain PHY events if LPM
is enabled; however, as DIPM commands are issued with stale
link->lpm_policy, they sometimes end up triggering these conditions
and get aborted leading to LPM configuration failure.

Fix it by updating link->lpm_policy before issuing DIPM enable
commands.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Kyle McMartin <kyle@mcmartin.ca>
Cc: stable@kernel.org
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

1 files changed, 14 insertions, 3 deletions

diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c
index 5e590504f3aa..17a637877d03 100644
--- a/drivers/ata/libata-eh.c
+++ b/drivers/ata/libata-eh.c
@@ -3275,6 +3275,7 @@ static int ata_eh_set_lpm(struct ata_link *link, enum ata_lpm_policy policy,
         struct ata_port *ap = ata_is_host_link(link) ? link->ap : NULL;
         struct ata_eh_context *ehc = &link->eh_context;
         struct ata_device *dev, *link_dev = NULL, *lpm_dev = NULL;
+        enum ata_lpm_policy old_policy = link->lpm_policy;
         unsigned int hints = ATA_LPM_EMPTY | ATA_LPM_HIPM;
         unsigned int err_mask;
         int rc;
@@ -3338,6 +3339,14 @@ static int ata_eh_set_lpm(struct ata_link *link, enum ata_lpm_policy policy,
                 goto fail;
         }
 
+        /*
+         * Low level driver acked the transition.  Issue DIPM command
+         * with the new policy set.
+         */
+        link->lpm_policy = policy;
+        if (ap && ap->slave_link)
+                ap->slave_link->lpm_policy = policy;
+
         /* host config updated, enable DIPM if transitioning to MIN_POWER */
         ata_for_each_dev(dev, link, ENABLED) {
                 if (policy == ATA_LPM_MIN_POWER && ata_id_has_dipm(dev->id)) {
@@ -3353,12 +3362,14 @@ static int ata_eh_set_lpm(struct ata_link *link, enum ata_lpm_policy policy,
                 }
         }
 
-        link->lpm_policy = policy;
-        if (ap && ap->slave_link)
-                ap->slave_link->lpm_policy = policy;
         return 0;
 
 fail:
+        /* restore the old policy */
+        link->lpm_policy = old_policy;
+        if (ap && ap->slave_link)
+                ap->slave_link->lpm_policy = old_policy;
+
         /* if no device or only one more chance is left, disable LPM */
         if (!dev || ehc->tries[dev->devno] <= 2) {
                 ata_link_printk(link, KERN_WARNING,