[PATCH] sata_sil24: reimplement hardreset

Reimplement hardreset according to the datasheet.  The old hardreset
didn't reset controller status and the controller might not be ready
after reset.  Also, as SStatus is a bit flakey after hardreset,
sata_std_hardrset() didn't use to wait long enough before proceeding.

Note that as we're not depending on SStatus, DET==1 condition cannot
be used to wait for link, so use shorter timeout for no device case.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

drivers/scsi/sata_sil24.c

@@ -521,10 +521,47 @@ static int sil24_softreset(struct ata_port *ap, unsigned int *class)
 
 static int sil24_hardreset(struct ata_port *ap, unsigned int *class)
 {
-	unsigned int dummy_class;
+	void __iomem *port = (void __iomem *)ap->ioaddr.cmd_addr;
+	const char *reason;
+	int tout_msec;
+	u32 tmp;
+
+	/* sil24 does the right thing(tm) without any protection */
+	ata_set_sata_spd(ap);
+
+	tout_msec = 100;
+	if (sata_dev_present(ap))
+		tout_msec = 5000;
+
+	writel(PORT_CS_DEV_RST, port + PORT_CTRL_STAT);
+	tmp = ata_wait_register(port + PORT_CTRL_STAT,
+				PORT_CS_DEV_RST, PORT_CS_DEV_RST, 10, tout_msec);
+
+	/* SStatus oscillates between zero and valid status for short
+	 * duration after DEV_RST, give it time to settle.
+	 */
+	msleep(100);
+
+	if (tmp & PORT_CS_DEV_RST) {
+		if (!sata_dev_present(ap))
+			return 0;
+		reason = "link not ready";
+		goto err;
+	}
+
+	if (ata_busy_sleep(ap, ATA_TMOUT_BOOT_QUICK, ATA_TMOUT_BOOT)) {
+		reason = "device not ready";
+		goto err;
+	}
 
-	/* sil24 doesn't report device signature after hard reset */
-	return sata_std_hardreset(ap, &dummy_class);
+	/* sil24 doesn't report device class code after hardreset,
+	 * leave *class alone.
+	 */
+	return 0;
+
+ err:
+	printk(KERN_ERR "ata%u: hardreset failed (%s)\n", ap->id, reason);
+	return -EIO;
 }
 
 static int sil24_probe_reset(struct ata_port *ap, unsigned int *classes)