[PATCH -mm] sata_nv: wait for response on entering/leaving ADMA mode

[Robert Hancock <hancockr@shaw.ca>]

Update sata_nv to wait for the controller to indicate via the status register
that it has entered the requested state when switching between ADMA mode and
register mode. This issue came up recently when debugging some problems with
cache flush command timeouts and while it didn't appear to fix that problem,
this is something we should likely be doing in any case.

Signed-off-by: Robert Hancock <hancockr@shaw.ca>

--- linux-2.6.20-rc6-mm3/drivers/ata/sata_nv.c	2007-02-04 21:48:25.000000000 -0600
+++ linux-2.6.20-rc6-mm3edit/drivers/ata/sata_nv.c	2007-02-04 22:13:36.000000000 -0600
@@ -507,14 +507,38 @@ static void nv_adma_register_mode(struct
{
	struct nv_adma_port_priv *pp = ap->private_data;
	void __iomem *mmio = pp->ctl_block;
-	u16 tmp;
+	u16 tmp, status;
+	int count = 0;

	if (pp->flags & NV_ADMA_PORT_REGISTER_MODE)
		return;

+	status = readw(mmio + NV_ADMA_STAT);
+	while(!(status & NV_ADMA_STAT_IDLE) && count < 20) {
+		ndelay(50);
+		status = readw(mmio + NV_ADMA_STAT);
+		count++;
+	}
+	if(count == 20)
+		ata_port_printk(ap, KERN_WARNING,
+			"timeout waiting for ADMA IDLE, stat=0x%hx\n",
+			status);
+
	tmp = readw(mmio + NV_ADMA_CTL);
	writew(tmp & ~NV_ADMA_CTL_GO, mmio + NV_ADMA_CTL);

+	count = 0;
+	status = readw(mmio + NV_ADMA_STAT);
+	while(!(status & NV_ADMA_STAT_LEGACY) && count < 20) {
+		ndelay(50);
+		status = readw(mmio + NV_ADMA_STAT);
+		count++;
+	}
+	if(count == 20)
+		ata_port_printk(ap, KERN_WARNING,
+			 "timeout waiting for ADMA LEGACY, stat=0x%hx\n",
+			 status);
+
	pp->flags |= NV_ADMA_PORT_REGISTER_MODE;
}

@@ -522,7 +546,8 @@ static void nv_adma_mode(struct ata_port
{
	struct nv_adma_port_priv *pp = ap->private_data;
	void __iomem *mmio = pp->ctl_block;
-	u16 tmp;
+	u16 tmp, status;
+	int count = 0;

	if (!(pp->flags & NV_ADMA_PORT_REGISTER_MODE))
		return;
@@ -532,6 +557,18 @@ static void nv_adma_mode(struct ata_port
	tmp = readw(mmio + NV_ADMA_CTL);
	writew(tmp | NV_ADMA_CTL_GO, mmio + NV_ADMA_CTL);

+	status = readw(mmio + NV_ADMA_STAT);
+	while(((status & NV_ADMA_STAT_LEGACY) ||
+	      !(status & NV_ADMA_STAT_IDLE)) && count < 20) {
+		ndelay(50);
+		status = readw(mmio + NV_ADMA_STAT);
+		count++;
+	}
+	if(count == 20)
+		ata_port_printk(ap, KERN_WARNING,
+			"timeout waiting for ADMA LEGACY clear and IDLE, stat=0x%hx\n",
+			status);
+
	pp->flags &= ~NV_ADMA_PORT_REGISTER_MODE;
}