sata_nv: reinstate nv_hardreset() for non generic controllers

Commit 2fd673ecf0378ddeeeb87b3605e50212e0c0ddc6 which tried to remove
hardreset for generic accidentally removed it for all flavors as all
others were inheriting from nv_generic_ops.  This patch reinstates
nv_hardreset() and puts it into nv_common_ops which all flavors
inherit from.  nv_generic_ops now inherits from nv_common_ops and
overrides .hardreset to ATA_OP_NULL.

While at it, explain why nv_hardreset and ATA_OP_NULL override are
necessary.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

1 files changed, 40 insertions, 6 deletions

diff --git a/drivers/ata/sata_nv.c b/drivers/ata/sata_nv.c
index 1e1f3f3757ae..14601dc05e41 100644
--- a/drivers/ata/sata_nv.c
+++ b/drivers/ata/sata_nv.c
@@ -309,6 +309,8 @@ static void nv_nf2_freeze(struct ata_port *ap);
 static void nv_nf2_thaw(struct ata_port *ap);
 static void nv_ck804_freeze(struct ata_port *ap);
 static void nv_ck804_thaw(struct ata_port *ap);
+static int nv_hardreset(struct ata_link *link, unsigned int *class,
+                        unsigned long deadline);
 static int nv_adma_slave_config(struct scsi_device *sdev);
 static int nv_adma_check_atapi_dma(struct ata_queued_cmd *qc);
 static void nv_adma_qc_prep(struct ata_queued_cmd *qc);
@@ -403,28 +405,45 @@ static struct scsi_host_template nv_swncq_sht = {
         .slave_configure        = nv_swncq_slave_config,
 };
 
-static struct ata_port_operations nv_generic_ops = {
+/* OSDL bz3352 reports that some nv controllers can't determine device
+ * signature reliably and nv_hardreset is implemented to work around
+ * the problem.  This was reported on nf3 and it's unclear whether any
+ * other controllers are affected.  However, the workaround has been
+ * applied to all variants and there isn't much to gain by trying to
+ * find out exactly which ones are affected at this point especially
+ * because NV has moved over to ahci for newer controllers.
+ */
+static struct ata_port_operations nv_common_ops = {
         .inherits               = &ata_bmdma_port_ops,
-        .hardreset              = ATA_OP_NULL,
+        .hardreset              = nv_hardreset,
         .scr_read               = nv_scr_read,
         .scr_write              = nv_scr_write,
 };
 
+/* OSDL bz11195 reports that link doesn't come online after hardreset
+ * on generic nv's and there have been several other similar reports
+ * on linux-ide.  Disable hardreset for generic nv's.
+ */
+static struct ata_port_operations nv_generic_ops = {
+        .inherits               = &nv_common_ops,
+        .hardreset              = ATA_OP_NULL,
+};
+
 static struct ata_port_operations nv_nf2_ops = {
-        .inherits               = &nv_generic_ops,
+        .inherits               = &nv_common_ops,
         .freeze                 = nv_nf2_freeze,
         .thaw                   = nv_nf2_thaw,
 };
 
 static struct ata_port_operations nv_ck804_ops = {
-        .inherits               = &nv_generic_ops,
+        .inherits               = &nv_common_ops,
         .freeze                 = nv_ck804_freeze,
         .thaw                   = nv_ck804_thaw,
         .host_stop              = nv_ck804_host_stop,
 };
 
 static struct ata_port_operations nv_adma_ops = {
-        .inherits               = &nv_generic_ops,
+        .inherits               = &nv_common_ops,
 
         .check_atapi_dma        = nv_adma_check_atapi_dma,
         .sff_tf_read            = nv_adma_tf_read,
@@ -448,7 +467,7 @@ static struct ata_port_operations nv_adma_ops = {
 };
 
 static struct ata_port_operations nv_swncq_ops = {
-        .inherits               = &nv_generic_ops,
+        .inherits               = &nv_common_ops,
 
         .qc_defer               = ata_std_qc_defer,
         .qc_prep                = nv_swncq_qc_prep,
@@ -1586,6 +1605,21 @@ static void nv_mcp55_thaw(struct ata_port *ap)
         ata_sff_thaw(ap);
 }
 
+static int nv_hardreset(struct ata_link *link, unsigned int *class,
+                        unsigned long deadline)
+{
+        int rc;
+
+        /* SATA hardreset fails to retrieve proper device signature on
+         * some controllers.  Request follow up SRST.  For more info,
+         * see http://bugzilla.kernel.org/show_bug.cgi?id=3352
+         */
+        rc = sata_sff_hardreset(link, class, deadline);
+        if (rc)
+                return rc;
+        return -EAGAIN;
+}
+
 static void nv_adma_error_handler(struct ata_port *ap)
 {
         struct nv_adma_port_priv *pp = ap->private_data;