[PATCH] libata: Marvell spinlock fixes and simplification

This should fix up lockups that people were seeing due to
improper spinlock placement.  Also, the start/stop DMA routines put
guarded trust in the cached state of DMA.
Signed-off-by: Brett Russ <russb@emc.com>
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>

drivers/scsi/sata_mv.c

@@ -35,7 +35,7 @@
 #include <asm/io.h>
 
 #define DRV_NAME	"sata_mv"
-#define DRV_VERSION	"0.22"
+#define DRV_VERSION	"0.23"
 
 enum {
 	/* BAR's are enumerated in terms of pci_resource_start() terms */
@@ -406,40 +406,30 @@ static void mv_irq_clear(struct ata_port *ap)
 {
 }
 
-static void mv_start_dma(void __iomem *base, struct mv_port_priv *pp,
-			 struct ata_port *ap)
+static void mv_start_dma(void __iomem *base, struct mv_port_priv *pp)
 {
-	unsigned long flags;
-
-	spin_lock_irqsave(&ap->host_set->lock, flags);
-	
-	writelfl(EDMA_EN, base + EDMA_CMD_OFS);
-	pp->pp_flags |= MV_PP_FLAG_EDMA_EN;
-
-	spin_unlock_irqrestore(&ap->host_set->lock, flags);
+	if (!(MV_PP_FLAG_EDMA_EN & pp->pp_flags)) {
+		writelfl(EDMA_EN, base + EDMA_CMD_OFS);
+		pp->pp_flags |= MV_PP_FLAG_EDMA_EN;
+	}
+	assert(EDMA_EN & readl(base + EDMA_CMD_OFS));
 }
 
 static void mv_stop_dma(struct ata_port *ap)
 {
 	void __iomem *port_mmio = mv_ap_base(ap);
 	struct mv_port_priv *pp	= ap->private_data;
-	unsigned long flags;
 	u32 reg;
 	int i;
 
-	spin_lock_irqsave(&ap->host_set->lock, flags);
-	
-	if (!(MV_PP_FLAG_EDMA_DS_ACT & pp->pp_flags) &&
-	    ((MV_PP_FLAG_EDMA_EN & pp->pp_flags) ||
-	     (EDMA_EN & readl(port_mmio + EDMA_CMD_OFS)))) {
-		/* Disable EDMA if we're not already trying to disable it
-		 * and it is currently active.   The disable bit auto clears.
+	if (MV_PP_FLAG_EDMA_EN & pp->pp_flags) {
+		/* Disable EDMA if active.   The disable bit auto clears.
 		 */
-		pp->pp_flags |= MV_PP_FLAG_EDMA_DS_ACT;
 		writelfl(EDMA_DS, port_mmio + EDMA_CMD_OFS);
 		pp->pp_flags &= ~MV_PP_FLAG_EDMA_EN;
-	}
-	spin_unlock_irqrestore(&ap->host_set->lock, flags);
+	} else {
+		assert(!(EDMA_EN & readl(port_mmio + EDMA_CMD_OFS)));
+  	}
 	
 	/* now properly wait for the eDMA to stop */
 	for (i = 1000; i > 0; i--) {
@@ -450,12 +440,9 @@ static void mv_stop_dma(struct ata_port *ap)
 		udelay(100);
 	}
 
-	spin_lock_irqsave(&ap->host_set->lock, flags);
-	pp->pp_flags &= ~MV_PP_FLAG_EDMA_DS_ACT;
-	spin_unlock_irqrestore(&ap->host_set->lock, flags);
-
 	if (EDMA_EN & reg) {
 		printk(KERN_ERR "ata%u: Unable to stop eDMA\n", ap->id);
+		/* FIXME: Consider doing a reset here to recover */
 	}
 }
 
@@ -716,8 +703,11 @@ static void mv_port_stop(struct ata_port *ap)
 {
 	struct device *dev = ap->host_set->dev;
 	struct mv_port_priv *pp = ap->private_data;
+	unsigned long flags;
 
+	spin_lock_irqsave(&ap->host_set->lock, flags);
 	mv_stop_dma(ap);
+	spin_unlock_irqrestore(&ap->host_set->lock, flags);
 
 	ap->private_data = NULL;
 	dma_free_coherent(dev, MV_PORT_PRIV_DMA_SZ, pp->crpb, pp->crpb_dma);
@@ -867,11 +857,7 @@ static int mv_qc_issue(struct ata_queued_cmd *qc)
 
 	mv_inc_q_index(&pp->req_producer);	/* now incr producer index */
 
-	if (!(MV_PP_FLAG_EDMA_EN & pp->pp_flags)) {
-		/* turn on EDMA if not already on */
-		mv_start_dma(port_mmio, pp, qc->ap);
-	}
-	assert(EDMA_EN & readl(port_mmio + EDMA_CMD_OFS));
+	mv_start_dma(port_mmio, pp);
 
 	/* and write the request in pointer to kick the EDMA to life */
 	in_ptr &= EDMA_REQ_Q_BASE_LO_MASK;
@@ -921,8 +907,12 @@ static void mv_err_intr(struct ata_port *ap)
 		serr = scr_read(ap, SCR_ERROR);
 		scr_write_flush(ap, SCR_ERROR, serr);
 	}
-	DPRINTK("port %u error; EDMA err cause: 0x%08x SERR: 0x%08x\n", 
-		ap->port_no, edma_err_cause, serr);
+	if (EDMA_ERR_SELF_DIS & edma_err_cause) {
+		struct mv_port_priv *pp	= ap->private_data;
+		pp->pp_flags &= ~MV_PP_FLAG_EDMA_EN;
+	}
+	DPRINTK(KERN_ERR "ata%u: port error; EDMA err cause: 0x%08x "
+		"SERR: 0x%08x\n", ap->id, edma_err_cause, serr);
 
 	/* Clear EDMA now that SERR cleanup done */
 	writelfl(0, port_mmio + EDMA_ERR_IRQ_CAUSE_OFS);
@@ -1034,7 +1024,7 @@ static irqreturn_t mv_interrupt(int irq, void *dev_instance,
 		printk(KERN_ERR DRV_NAME ": PCI ERROR; PCI IRQ cause=0x%08x\n",
 		       readl(mmio + PCI_IRQ_CAUSE_OFS));
 
-		VPRINTK("All regs @ PCI error\n");
+		DPRINTK("All regs @ PCI error\n");
 		mv_dump_all_regs(mmio, -1, to_pci_dev(host_set->dev));
 
 		writelfl(0, mmio + PCI_IRQ_CAUSE_OFS);