ahci: separate out ahci_kick_engine()

Separate out stop_engine - CLO - start_engine sequence from
ahci_softreset() and ahci_clo() into ahci_reset_engine() and use it in
ahci_softreset() and ahci_post_internal_cmd().  The function will also
be used to prepare for and clean up after PMP register access
commands.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

1 files changed, 36 insertions, 33 deletions

diff --git a/drivers/ata/ahci.c b/drivers/ata/ahci.c
index 0451600bdcc6..1be238def0ed 100644
--- a/drivers/ata/ahci.c
+++ b/drivers/ata/ahci.c
@@ -948,25 +948,49 @@ static void ahci_fill_cmd_slot(struct ahci_port_priv *pp, unsigned int tag,
         pp->cmd_slot[tag].tbl_addr_hi = cpu_to_le32((cmd_tbl_dma >> 16) >> 16);
 }
 
-static int ahci_clo(struct ata_port *ap)
+static int ahci_kick_engine(struct ata_port *ap, int force_restart)
 {
         void __iomem *port_mmio = ap->ioaddr.cmd_addr;
         struct ahci_host_priv *hpriv = ap->host->private_data;
         u32 tmp;
+        int busy, rc;
 
-        if (!(hpriv->cap & HOST_CAP_CLO))
-                return -EOPNOTSUPP;
+        /* do we need to kick the port? */
+        busy = ahci_check_status(ap) & (ATA_BUSY | ATA_DRQ);
+        if (!busy && !force_restart)
+                return 0;
+
+        /* stop engine */
+        rc = ahci_stop_engine(ap);
+        if (rc)
+                goto out_restart;
+
+        /* need to do CLO? */
+        if (!busy) {
+                rc = 0;
+                goto out_restart;
+        }
+
+        if (!(hpriv->cap & HOST_CAP_CLO)) {
+                rc = -EOPNOTSUPP;
+                goto out_restart;
+        }
 
+        /* perform CLO */
         tmp = readl(port_mmio + PORT_CMD);
         tmp |= PORT_CMD_CLO;
         writel(tmp, port_mmio + PORT_CMD);
 
+        rc = 0;
         tmp = ata_wait_register(port_mmio + PORT_CMD,
                                 PORT_CMD_CLO, PORT_CMD_CLO, 1, 500);
         if (tmp & PORT_CMD_CLO)
-                return -EIO;
+                rc = -EIO;
 
-        return 0;
+        /* restart engine */
+ out_restart:
+        ahci_start_engine(ap);
+        return rc;
 }
 
 static int ahci_softreset(struct ata_port *ap, unsigned int *class,
@@ -991,27 +1015,10 @@ static int ahci_softreset(struct ata_port *ap, unsigned int *class,
         }
 
         /* prepare for SRST (AHCI-1.1 10.4.1) */
-        rc = ahci_stop_engine(ap);
-        if (rc) {
-                reason = "failed to stop engine";
-                goto fail_restart;
-        }
-
-        /* check BUSY/DRQ, perform Command List Override if necessary */
-        if (ahci_check_status(ap) & (ATA_BUSY | ATA_DRQ)) {
-                rc = ahci_clo(ap);
-
-                if (rc == -EOPNOTSUPP) {
-                        reason = "port busy but CLO unavailable";
-                        goto fail_restart;
-                } else if (rc) {
-                        reason = "port busy but CLO failed";
-                        goto fail_restart;
-                }
-        }
-
-        /* restart engine */
-        ahci_start_engine(ap);
+        rc = ahci_kick_engine(ap, 1);
+        if (rc)
+                ata_port_printk(ap, KERN_WARNING,
+                                "failed to reset engine (errno=%d)", rc);
 
         ata_tf_init(ap->device, &tf);
         fis = pp->cmd_tbl;
@@ -1070,8 +1077,6 @@ static int ahci_softreset(struct ata_port *ap, unsigned int *class,
         DPRINTK("EXIT, class=%u\n", *class);
         return 0;
 
- fail_restart:
-        ahci_start_engine(ap);
  fail:
         ata_port_printk(ap, KERN_ERR, "softreset failed (%s)\n", reason);
         return rc;
@@ -1516,11 +1521,9 @@ static void ahci_post_internal_cmd(struct ata_queued_cmd *qc)
 {
         struct ata_port *ap = qc->ap;
 
-        if (qc->flags & ATA_QCFLAG_FAILED) {
-                /* make DMA engine forget about the failed command */
-                ahci_stop_engine(ap);
-                ahci_start_engine(ap);
-        }
+        /* make DMA engine forget about the failed command */
+        if (qc->flags & ATA_QCFLAG_FAILED)
+                ahci_kick_engine(ap, 1);
 }
 
 static int ahci_port_resume(struct ata_port *ap)