libata: disable LPM for some WD SATA-I devices

For some reason, some early WD drives spin up and down drives
erratically when the link is put into slumber mode which can reduce
the life expectancy of the device significantly.  Unfortunately, we
don't have full list of devices and given the nature of the issue it'd
be better to err on the side of false positives than the other way
around.  Let's disable LPM on all WD devices which match one of the
known problematic model prefixes and are SATA-I.

As horkage list doesn't support matching SATA capabilities, this is
implemented as two horkages - WD_BROKEN_LPM and NOLPM.  The former is
set for the known prefixes and sets the latter if the matched device
is SATA-I.

Note that this isn't optimal as this disables all LPM operations and
partial link power state reportedly works fine on these; however, the
way LPM is implemented in libata makes it difficult to precisely map
libata LPM setting to specific link power state.  Well, these devices
are already fairly outdated.  Let's just disable whole LPM for now.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-and-tested-by: Nikos Barkas <levelwol@gmail.com>
Reported-and-tested-by: Ioannis Barkas <risc4all@yahoo.com>
References: https://bugzilla.kernel.org/show_bug.cgi?id=57211
Cc: stable@vger.kernel.org

1 files changed, 15 insertions, 3 deletions

diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index 176f62950e3d..75ef9527603e 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -111,12 +111,14 @@ static const char *ata_lpm_policy_names[] = {
         [ATA_LPM_MIN_POWER]     = "min_power",
 };
 
-static ssize_t ata_scsi_lpm_store(struct device *dev,
+static ssize_t ata_scsi_lpm_store(struct device *device,
                                   struct device_attribute *attr,
                                   const char *buf, size_t count)
 {
-        struct Scsi_Host *shost = class_to_shost(dev);
+        struct Scsi_Host *shost = class_to_shost(device);
         struct ata_port *ap = ata_shost_to_port(shost);
+        struct ata_link *link;
+        struct ata_device *dev;
         enum ata_lpm_policy policy;
         unsigned long flags;
 
@@ -132,10 +134,20 @@ static ssize_t ata_scsi_lpm_store(struct device *dev,
                 return -EINVAL;
 
         spin_lock_irqsave(ap->lock, flags);
+
+        ata_for_each_link(link, ap, EDGE) {
+                ata_for_each_dev(dev, &ap->link, ENABLED) {
+                        if (dev->horkage & ATA_HORKAGE_NOLPM) {
+                                count = -EOPNOTSUPP;
+                                goto out_unlock;
+                        }
+                }
+        }
+
         ap->target_lpm_policy = policy;
         ata_port_schedule_eh(ap);
+out_unlock:
         spin_unlock_irqrestore(ap->lock, flags);
-
         return count;
 }