[libata ahci] set port ATAPI bit correctly

Although according to the documentation this largely only affects
desktop LED control, let's make sure we set the ATAPI bit when we
have an ATAPI device attached to the port.

drivers/scsi/ahci.c

@@ -134,6 +134,7 @@ enum {
 				  PORT_IRQ_D2H_REG_FIS,
 
 	/* PORT_CMD bits */
+	PORT_CMD_ATAPI		= (1 << 24), /* Device is ATAPI */
 	PORT_CMD_LIST_ON	= (1 << 15), /* cmd list DMA engine running */
 	PORT_CMD_FIS_ON		= (1 << 14), /* FIS DMA engine running */
 	PORT_CMD_FIS_RX		= (1 << 4), /* Enable FIS receive DMA engine */
@@ -441,7 +442,7 @@ static void ahci_phy_reset(struct ata_port *ap)
 	void __iomem *port_mmio = (void __iomem *) ap->ioaddr.cmd_addr;
 	struct ata_taskfile tf;
 	struct ata_device *dev = &ap->device[0];
-	u32 tmp;
+	u32 new_tmp, tmp;
 
 	__sata_phy_reset(ap);
 
@@ -455,8 +456,21 @@ static void ahci_phy_reset(struct ata_port *ap)
 	tf.nsect	= (tmp)		& 0xff;
 
 	dev->class = ata_dev_classify(&tf);
-	if (!ata_dev_present(dev))
+	if (!ata_dev_present(dev)) {
 		ata_port_disable(ap);
+		return;
+	}
+
+	/* Make sure port's ATAPI bit is set appropriately */
+	new_tmp = tmp = readl(port_mmio + PORT_CMD);
+	if (dev->class == ATA_DEV_ATAPI)
+		new_tmp |= PORT_CMD_ATAPI;
+	else
+		new_tmp &= ~PORT_CMD_ATAPI;
+	if (new_tmp != tmp) {
+		writel(new_tmp, port_mmio + PORT_CMD);
+		readl(port_mmio + PORT_CMD); /* flush */
+	}
 }
 
 static u8 ahci_check_status(struct ata_port *ap)