[libata ata_piix] Make sure annoying BIOSen don't disable our interrupts

drivers/scsi/ata_piix.c

@@ -28,12 +28,13 @@
 #include <linux/libata.h>
 
 #define DRV_NAME	"ata_piix"
-#define DRV_VERSION	"1.00"
+#define DRV_VERSION	"1.01"
 
 enum {
 	PIIX_IOCFG		= 0x54, /* IDE I/O configuration register */
 	ICH5_PCS		= 0x92,	/* port control and status */
 
+	PIIX_FLAG_CHECKINTR	= (1 << 29), /* make sure PCI INTx enabled */
 	PIIX_FLAG_COMBINED	= (1 << 30), /* combined mode possible */
 
 	PIIX_COMB_PRI		= (1 << 0), /* combined mode, PATA primary */
@@ -163,7 +164,8 @@ static struct ata_port_info piix_port_info[] = {
 	/* ich5_pata */
 	{
 		.sht		= &piix_sht,
-		.host_flags	= ATA_FLAG_SLAVE_POSS | ATA_FLAG_SRST,
+		.host_flags	= ATA_FLAG_SLAVE_POSS | ATA_FLAG_SRST |
+				  PIIX_FLAG_CHECKINTR,
 		.pio_mask	= 0x03,	/* pio3-4 */
 		.udma_mask	= ATA_UDMA_MASK_40C, /* FIXME: cbl det */
 		.port_ops	= &piix_pata_ops,
@@ -172,8 +174,8 @@ static struct ata_port_info piix_port_info[] = {
 	/* ich5_sata */
 	{
 		.sht		= &piix_sht,
-		.host_flags	= ATA_FLAG_SATA | PIIX_FLAG_COMBINED |
-				  ATA_FLAG_SRST,
+		.host_flags	= ATA_FLAG_SATA | ATA_FLAG_SRST |
+				  PIIX_FLAG_COMBINED | PIIX_FLAG_CHECKINTR,
 		.pio_mask	= 0x03,	/* pio3-4 */
 		.udma_mask	= 0x7f,	/* udma0-6 ; FIXME */
 		.port_ops	= &piix_sata_ops,
@@ -518,6 +520,18 @@ static void piix_probe_combined (struct pci_dev *pdev, unsigned int *mask)
 		*mask |= PIIX_COMB_PRI;
 }
 
+/* move to PCI layer, integrate w/ MSI stuff */
+static void pci_enable_intx(struct pci_dev *pdev)
+{
+	u16 pci_command;
+
+	pci_read_config_word(pdev, PCI_COMMAND, &pci_command);
+	if (pci_command & PCI_COMMAND_INTX_DISABLE) {
+		pci_command &= ~PCI_COMMAND_INTX_DISABLE;
+		pci_write_config_word(pdev, PCI_COMMAND, pci_command);
+	}
+}
+
 /**
  *	piix_init_one - Register PIIX ATA PCI device with kernel services
  *	@pdev: PCI device to register
@@ -552,6 +566,15 @@ static int piix_init_one (struct pci_dev *pdev, const struct pci_device_id *ent)
 	if (port_info[0]->host_flags & PIIX_FLAG_COMBINED)
 		piix_probe_combined(pdev, &combined);
 
+	/* On ICH5, some BIOSen disable the interrupt using the
+	 * PCI_COMMAND_INTX_DISABLE bit added in PCI 2.3.
+	 * On ICH6, this bit has the same effect, but only when
+	 * MSI is disabled (and it is disabled, as we don't use
+	 * message-signalled interrupts currently).
+	 */
+	if (port_info[0]->host_flags & PIIX_FLAG_CHECKINTR)
+		pci_enable_intx(pdev);
+
 	if (combined & PIIX_COMB_PRI)
 		sata_comb = 1;
 	else if (combined & PIIX_COMB_SEC)