[PATCH] The redefinition of ahci_start_engine() and ahci_stop_engine()

- Make ahci_start_engine() and ahci_stop_engine() more consistent with
  AHCI spec 1.1
- Change their input parameter from ap to port_mmio
- Update the existing users of ahci_start_engine() and ahci_stop_engine()

Signed-off-by: Forrest Zhao <forrest.zhao@intel.com>
Signed-off-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Jens Axboe <axboe@suse.de>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

1 files changed, 57 insertions, 25 deletions

diff --git a/drivers/scsi/ahci.c b/drivers/scsi/ahci.c
index 77e7202a0eba..f1516ca2c52a 100644
--- a/drivers/scsi/ahci.c
+++ b/drivers/scsi/ahci.c
@@ -205,6 +205,8 @@ static irqreturn_t ahci_interrupt (int irq, void *dev_instance, struct pt_regs *
 static void ahci_irq_clear(struct ata_port *ap);
 static int ahci_port_start(struct ata_port *ap);
 static void ahci_port_stop(struct ata_port *ap);
+static int ahci_start_engine(void __iomem *port_mmio);
+static int ahci_stop_engine(void __iomem *port_mmio);
 static void ahci_tf_read(struct ata_port *ap, struct ata_taskfile *tf);
 static void ahci_qc_prep(struct ata_queued_cmd *qc);
 static u8 ahci_check_status(struct ata_port *ap);
@@ -508,41 +510,64 @@ static void ahci_scr_write (struct ata_port *ap, unsigned int sc_reg_in,
         writel(val, (void __iomem *) ap->ioaddr.scr_addr + (sc_reg * 4));
 }
 
-static int ahci_stop_engine(struct ata_port *ap)
+static int ahci_stop_engine(void __iomem *port_mmio)
 {
-        void __iomem *mmio = ap->host_set->mmio_base;
-        void __iomem *port_mmio = ahci_port_base(mmio, ap->port_no);
-        int work;
         u32 tmp;
 
         tmp = readl(port_mmio + PORT_CMD);
+
+        /* Check if the HBA is idle */
+        if ((tmp & (PORT_CMD_START | PORT_CMD_LIST_ON)) == 0)
+                return 0;
+
+        /* Setting HBA to idle */
         tmp &= ~PORT_CMD_START;
         writel(tmp, port_mmio + PORT_CMD);
 
-        /* wait for engine to stop.  TODO: this could be
+        /* wait for engine to stop. This could be
          * as long as 500 msec
          */
-        work = 1000;
-        while (work-- > 0) {
-                tmp = readl(port_mmio + PORT_CMD);
-                if ((tmp & PORT_CMD_LIST_ON) == 0)
-                        return 0;
-                udelay(10);
-        }
+        tmp = ata_wait_register(port_mmio + PORT_CMD,
+                                PORT_CMD_LIST_ON, PORT_CMD_LIST_ON, 1, 500);
+        if(tmp & PORT_CMD_LIST_ON)
+                return -EIO;
 
-        return -EIO;
+        return 0;
 }
 
-static void ahci_start_engine(struct ata_port *ap)
+static int ahci_start_engine(void __iomem *port_mmio)
 {
-        void __iomem *mmio = ap->host_set->mmio_base;
-        void __iomem *port_mmio = ahci_port_base(mmio, ap->port_no);
         u32 tmp;
 
+        /*
+         * Get current status
+         */
         tmp = readl(port_mmio + PORT_CMD);
+
+        /*
+         * AHCI rev 1.1 section 10.3.1:
+         * Software shall not set PxCMD.ST to '1' until it verifies
+         * that PxCMD.CR is '0' and has set PxCMD.FRE to '1'
+         */
+        if ((tmp & PORT_CMD_FIS_RX) == 0)
+                return -EPERM;
+
+        /*
+         * wait for engine to become idle.
+         */
+        tmp = ata_wait_register(port_mmio + PORT_CMD,
+                                PORT_CMD_LIST_ON, PORT_CMD_LIST_ON, 1,500);
+        if(tmp & PORT_CMD_LIST_ON)
+                return -EBUSY;
+
+        /*
+         * Start DMA
+         */
         tmp |= PORT_CMD_START;
         writel(tmp, port_mmio + PORT_CMD);
         readl(port_mmio + PORT_CMD); /* flush */
+
+        return 0;
 }
 
 static unsigned int ahci_dev_classify(struct ata_port *ap)
@@ -626,7 +651,7 @@ 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);
+        rc = ahci_stop_engine(port_mmio);
         if (rc) {
                 reason = "failed to stop engine";
                 goto fail_restart;
@@ -647,7 +672,7 @@ static int ahci_softreset(struct ata_port *ap, unsigned int *class)
         }
 
         /* restart engine */
-        ahci_start_engine(ap);
+        ahci_start_engine(port_mmio);
 
         ata_tf_init(ap->device, &tf);
         fis = pp->cmd_tbl;
@@ -706,7 +731,7 @@ static int ahci_softreset(struct ata_port *ap, unsigned int *class)
         return 0;
 
  fail_restart:
-        ahci_start_engine(ap);
+        ahci_start_engine(port_mmio);
  fail:
         ata_port_printk(ap, KERN_ERR, "softreset failed (%s)\n", reason);
         return rc;
@@ -717,11 +742,13 @@ static int ahci_hardreset(struct ata_port *ap, unsigned int *class)
         struct ahci_port_priv *pp = ap->private_data;
         u8 *d2h_fis = pp->rx_fis + RX_FIS_D2H_REG;
         struct ata_taskfile tf;
+        void __iomem *mmio = ap->host_set->mmio_base;
+        void __iomem *port_mmio = ahci_port_base(mmio, ap->port_no);
         int rc;
 
         DPRINTK("ENTER\n");
 
-        ahci_stop_engine(ap);
+        ahci_stop_engine(port_mmio);
 
         /* clear D2H reception area to properly wait for D2H FIS */
         ata_tf_init(ap->device, &tf);
@@ -730,7 +757,7 @@ static int ahci_hardreset(struct ata_port *ap, unsigned int *class)
 
         rc = sata_std_hardreset(ap, class);
 
-        ahci_start_engine(ap);
+        ahci_start_engine(port_mmio);
 
         if (rc == 0 && ata_port_online(ap))
                 *class = ahci_dev_classify(ap);
@@ -1052,10 +1079,13 @@ static void ahci_thaw(struct ata_port *ap)
 
 static void ahci_error_handler(struct ata_port *ap)
 {
+        void __iomem *mmio = ap->host_set->mmio_base;
+        void __iomem *port_mmio = ahci_port_base(mmio, ap->port_no);
+
         if (!(ap->pflags & ATA_PFLAG_FROZEN)) {
                 /* restart engine */
-                ahci_stop_engine(ap);
-                ahci_start_engine(ap);
+                ahci_stop_engine(port_mmio);
+                ahci_start_engine(port_mmio);
         }
 
         /* perform recovery */
@@ -1066,14 +1096,16 @@ static void ahci_error_handler(struct ata_port *ap)
 static void ahci_post_internal_cmd(struct ata_queued_cmd *qc)
 {
         struct ata_port *ap = qc->ap;
+        void __iomem *mmio = ap->host_set->mmio_base;
+        void __iomem *port_mmio = ahci_port_base(mmio, ap->port_no);
 
         if (qc->flags & ATA_QCFLAG_FAILED)
                 qc->err_mask |= AC_ERR_OTHER;
 
         if (qc->err_mask) {
                 /* make DMA engine forget about the failed command */
-                ahci_stop_engine(ap);
-                ahci_start_engine(ap);
+                ahci_stop_engine(port_mmio);
+                ahci_start_engine(port_mmio);
         }
 }