[PATCH] ata_piix: apply device detection via polling IDENTIFY

PATA PIIX uses reset signature + TF r/w test for device presence
detection, which doesn't always work.  It sometimes reports phantom
device which results in IDENTIFY timeouts.

SATA PIIX uses some combination of PCS + reset signature + TF r/w test
for device presence detection.  No combination satifies all and for
some controllers, there doesn't seem to be any combination which
works reliably.

This patch makes both PATA and SATA piix's use reset signature + TF
r/w + polling IDENTIFY for device detection.  This is what the old
libata (before irq-pio and new EH) did and what IDE does.

This patch also removes now obsolete PIIX_FLAG_IGNORE_PCS, force_pcs
and related code.
Signed-off-by: Jeff Garzik <jeff@garzik.org>

drivers/ata/ata_piix.c

@@ -101,13 +101,13 @@ enum {
 	ICH5_PCS		= 0x92,	/* port control and status */
 	PIIX_SCC		= 0x0A, /* sub-class code register */
 
-	PIIX_FLAG_IGNORE_PCS	= (1 << 25), /* ignore PCS present bits */
 	PIIX_FLAG_SCR		= (1 << 26), /* SCR available */
 	PIIX_FLAG_AHCI		= (1 << 27), /* AHCI possible */
 	PIIX_FLAG_CHECKINTR	= (1 << 28), /* make sure PCI INTx enabled */
 
-	PIIX_PATA_FLAGS		= ATA_FLAG_SLAVE_POSS,
-	PIIX_SATA_FLAGS		= ATA_FLAG_SATA | PIIX_FLAG_CHECKINTR,
+	PIIX_PATA_FLAGS		= ATA_FLAG_SLAVE_POSS | ATA_FLAG_DETECT_POLLING,
+	PIIX_SATA_FLAGS		= ATA_FLAG_SATA | PIIX_FLAG_CHECKINTR |
+				  ATA_FLAG_DETECT_POLLING,
 
 	/* combined mode.  if set, PATA is channel 0.
 	 * if clear, PATA is channel 1.
@@ -490,7 +490,7 @@ static struct ata_port_info piix_port_info[] = {
 	/* ich5_sata: 5 */
 	{
 		.sht		= &piix_sht,
-		.flags		= PIIX_SATA_FLAGS | PIIX_FLAG_IGNORE_PCS,
+		.flags		= PIIX_SATA_FLAGS,
 		.pio_mask	= 0x1f,	/* pio0-4 */
 		.mwdma_mask	= 0x07, /* mwdma0-2 */
 		.udma_mask	= 0x7f,	/* udma0-6 */
@@ -500,7 +500,7 @@ static struct ata_port_info piix_port_info[] = {
 	/* i6300esb_sata: 6 */
 	{
 		.sht		= &piix_sht,
-		.flags		= PIIX_SATA_FLAGS | PIIX_FLAG_IGNORE_PCS,
+		.flags		= PIIX_SATA_FLAGS,
 		.pio_mask	= 0x1f,	/* pio0-4 */
 		.mwdma_mask	= 0x07, /* mwdma0-2 */
 		.udma_mask	= 0x7f,	/* udma0-6 */
@@ -563,11 +563,6 @@ MODULE_LICENSE("GPL");
 MODULE_DEVICE_TABLE(pci, piix_pci_tbl);
 MODULE_VERSION(DRV_VERSION);
 
-static int force_pcs = 0;
-module_param(force_pcs, int, 0444);
-MODULE_PARM_DESC(force_pcs, "force honoring or ignoring PCS to work around "
-		 "device mis-detection (0=default, 1=ignore PCS, 2=honor PCS)");
-
 struct ich_laptop {
 	u16 device;
 	u16 subvendor;
@@ -685,84 +680,9 @@ static void ich_pata_error_handler(struct ata_port *ap)
 			   ata_std_postreset);
 }
 
-/**
- *	piix_sata_present_mask - determine present mask for SATA host controller
- *	@ap: Target port
- *
- *	Reads SATA PCI device's PCI config register Port Configuration
- *	and Status (PCS) to determine port and device availability.
- *
- *	LOCKING:
- *	None (inherited from caller).
- *
- *	RETURNS:
- *	determined present_mask
- */
-static unsigned int piix_sata_present_mask(struct ata_port *ap)
-{
-	struct pci_dev *pdev = to_pci_dev(ap->host->dev);
-	struct piix_host_priv *hpriv = ap->host->private_data;
-	const unsigned int *map = hpriv->map;
-	int base = 2 * ap->port_no;
-	unsigned int present_mask = 0;
-	int port, i;
-	u16 pcs;
-
-	pci_read_config_word(pdev, ICH5_PCS, &pcs);
-	DPRINTK("ata%u: ENTER, pcs=0x%x base=%d\n", ap->id, pcs, base);
-
-	for (i = 0; i < 2; i++) {
-		port = map[base + i];
-		if (port < 0)
-			continue;
-		if ((ap->flags & PIIX_FLAG_IGNORE_PCS) ||
-		    (pcs & 1 << (hpriv->map_db->present_shift + port)))
-			present_mask |= 1 << i;
-	}
-
-	DPRINTK("ata%u: LEAVE, pcs=0x%x present_mask=0x%x\n",
-		ap->id, pcs, present_mask);
-
-	return present_mask;
-}
-
-/**
- *	piix_sata_softreset - reset SATA host port via ATA SRST
- *	@ap: port to reset
- *	@classes: resulting classes of attached devices
- *
- *	Reset SATA host port via ATA SRST.  On controllers with
- *	reliable PCS present bits, the bits are used to determine
- *	device presence.
- *
- *	LOCKING:
- *	Kernel thread context (may sleep)
- *
- *	RETURNS:
- *	0 on success, -errno otherwise.
- */
-static int piix_sata_softreset(struct ata_port *ap, unsigned int *classes)
-{
-	unsigned int present_mask;
-	int i, rc;
-
-	present_mask = piix_sata_present_mask(ap);
-
-	rc = ata_std_softreset(ap, classes);
-	if (rc)
-		return rc;
-
-	for (i = 0; i < ATA_MAX_DEVICES; i++) {
-		if (!(present_mask & (1 << i)))
-			classes[i] = ATA_DEV_NONE;
-	}
-
-	return 0;
-}
-
 static void piix_sata_error_handler(struct ata_port *ap)
 {
-	ata_bmdma_drive_eh(ap, ata_std_prereset, piix_sata_softreset, NULL,
+	ata_bmdma_drive_eh(ap, ata_std_prereset, ata_std_softreset, NULL,
 			   ata_std_postreset);
 }
 
@@ -1077,18 +997,6 @@ static void __devinit piix_init_pcs(struct pci_dev *pdev,
 		pci_write_config_word(pdev, ICH5_PCS, new_pcs);
 		msleep(150);
 	}
-
-	if (force_pcs == 1) {
-		dev_printk(KERN_INFO, &pdev->dev,
-			   "force ignoring PCS (0x%x)\n", new_pcs);
-		pinfo[0].flags |= PIIX_FLAG_IGNORE_PCS;
-		pinfo[1].flags |= PIIX_FLAG_IGNORE_PCS;
-	} else if (force_pcs == 2) {
-		dev_printk(KERN_INFO, &pdev->dev,
-			   "force honoring PCS (0x%x)\n", new_pcs);
-		pinfo[0].flags &= ~PIIX_FLAG_IGNORE_PCS;
-		pinfo[1].flags &= ~PIIX_FLAG_IGNORE_PCS;
-	}
 }
 
 static void __devinit piix_init_sata_map(struct pci_dev *pdev,