libata-pmp-prep: implement sata_async_notification()

AN serves multiple purposes.  For ATAPI, it's used for media change
notification.  For PMP, for downstream PHY status change notification.
Implement sata_async_notification() which demultiplexes AN.

To avoid unnecessary port events, ATAPI AN is not enabled if PMP is
attached but SNTF is not available.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Cc: Kriten Carlson Accardi <kristen.c.accardi@intel.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

1 files changed, 9 insertions, 4 deletions

diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 376dbd80cc93..8b08e7bdd24d 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -2016,6 +2016,7 @@ int ata_dev_configure(struct ata_device *dev)
         else if (dev->class == ATA_DEV_ATAPI) {
                 const char *cdb_intr_string = "";
                 const char *atapi_an_string = "";
+                u32 sntf;
 
                 rc = atapi_cdb_len(id);
                 if ((rc < 12) || (rc > ATAPI_CDB_LEN)) {
@@ -2027,11 +2028,14 @@ int ata_dev_configure(struct ata_device *dev)
                 }
                 dev->cdb_len = (unsigned int) rc;
 
-                /*
-                 * check to see if this ATAPI device supports
-                 * Asynchronous Notification
+                /* Enable ATAPI AN if both the host and device have
+                 * the support.  If PMP is attached, SNTF is required
+                 * to enable ATAPI AN to discern between PHY status
+                 * changed notifications and ATAPI ANs.
                  */
-                if ((ap->flags & ATA_FLAG_AN) && ata_id_has_atapi_AN(id)) {
+                if ((ap->flags & ATA_FLAG_AN) && ata_id_has_atapi_AN(id) &&
+                    (!ap->nr_pmp_links ||
+                     sata_scr_read(&ap->link, SCR_NOTIFICATION, &sntf) == 0)) {
                         unsigned int err_mask;
 
                         /* issue SET feature command to turn this on */
@@ -7248,6 +7252,7 @@ EXPORT_SYMBOL_GPL(ata_port_schedule_eh);
 EXPORT_SYMBOL_GPL(ata_link_abort);
 EXPORT_SYMBOL_GPL(ata_port_abort);
 EXPORT_SYMBOL_GPL(ata_port_freeze);
+EXPORT_SYMBOL_GPL(sata_async_notification);
 EXPORT_SYMBOL_GPL(ata_eh_freeze_port);
 EXPORT_SYMBOL_GPL(ata_eh_thaw_port);
 EXPORT_SYMBOL_GPL(ata_eh_qc_complete);