ahci: avoton port-disable reset-quirk

commit dbfe8ef5 upstream.

Avoton AHCI occasionally sees drive probe timeouts at driver load time.
When this happens SCR_STATUS indicates device detected, but no D2H FIS
reception.  Reset the internal link state machines by bouncing
port-enable in the PCS register when this occurs.
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

drivers/ata/ahci.c

@@ -66,6 +66,7 @@ enum board_ids {
 	board_ahci_yes_fbs,
 
 	/* board IDs for specific chipsets in alphabetical order */
+	board_ahci_avn,
 	board_ahci_mcp65,
 	board_ahci_mcp77,
 	board_ahci_mcp89,
@@ -84,6 +85,8 @@ enum board_ids {
 static int ahci_init_one(struct pci_dev *pdev, const struct pci_device_id *ent);
 static int ahci_vt8251_hardreset(struct ata_link *link, unsigned int *class,
 				 unsigned long deadline);
+static int ahci_avn_hardreset(struct ata_link *link, unsigned int *class,
+			      unsigned long deadline);
 static void ahci_mcp89_apple_enable(struct pci_dev *pdev);
 static bool is_mcp89_apple(struct pci_dev *pdev);
 static int ahci_p5wdh_hardreset(struct ata_link *link, unsigned int *class,
@@ -107,6 +110,11 @@ static struct ata_port_operations ahci_p5wdh_ops = {
 	.hardreset		= ahci_p5wdh_hardreset,
 };
 
+static struct ata_port_operations ahci_avn_ops = {
+	.inherits		= &ahci_ops,
+	.hardreset		= ahci_avn_hardreset,
+};
+
 static const struct ata_port_info ahci_port_info[] = {
 	/* by features */
 	[board_ahci] = {
@@ -151,6 +159,12 @@ static const struct ata_port_info ahci_port_info[] = {
 		.port_ops	= &ahci_ops,
 	},
 	/* by chipsets */
+	[board_ahci_avn] = {
+		.flags		= AHCI_FLAG_COMMON,
+		.pio_mask	= ATA_PIO4,
+		.udma_mask	= ATA_UDMA6,
+		.port_ops	= &ahci_avn_ops,
+	},
 	[board_ahci_mcp65] = {
 		AHCI_HFLAGS	(AHCI_HFLAG_NO_FPDMA_AA | AHCI_HFLAG_NO_PMP |
 				 AHCI_HFLAG_YES_NCQ),
@@ -290,14 +304,14 @@ static const struct pci_device_id ahci_pci_tbl[] = {
 	{ PCI_VDEVICE(INTEL, 0x1f27), board_ahci }, /* Avoton RAID */
 	{ PCI_VDEVICE(INTEL, 0x1f2e), board_ahci }, /* Avoton RAID */
 	{ PCI_VDEVICE(INTEL, 0x1f2f), board_ahci }, /* Avoton RAID */
-	{ PCI_VDEVICE(INTEL, 0x1f32), board_ahci }, /* Avoton AHCI */
-	{ PCI_VDEVICE(INTEL, 0x1f33), board_ahci }, /* Avoton AHCI */
-	{ PCI_VDEVICE(INTEL, 0x1f34), board_ahci }, /* Avoton RAID */
-	{ PCI_VDEVICE(INTEL, 0x1f35), board_ahci }, /* Avoton RAID */
-	{ PCI_VDEVICE(INTEL, 0x1f36), board_ahci }, /* Avoton RAID */
-	{ PCI_VDEVICE(INTEL, 0x1f37), board_ahci }, /* Avoton RAID */
-	{ PCI_VDEVICE(INTEL, 0x1f3e), board_ahci }, /* Avoton RAID */
-	{ PCI_VDEVICE(INTEL, 0x1f3f), board_ahci }, /* Avoton RAID */
+	{ PCI_VDEVICE(INTEL, 0x1f32), board_ahci_avn }, /* Avoton AHCI */
+	{ PCI_VDEVICE(INTEL, 0x1f33), board_ahci_avn }, /* Avoton AHCI */
+	{ PCI_VDEVICE(INTEL, 0x1f34), board_ahci_avn }, /* Avoton RAID */
+	{ PCI_VDEVICE(INTEL, 0x1f35), board_ahci_avn }, /* Avoton RAID */
+	{ PCI_VDEVICE(INTEL, 0x1f36), board_ahci_avn }, /* Avoton RAID */
+	{ PCI_VDEVICE(INTEL, 0x1f37), board_ahci_avn }, /* Avoton RAID */
+	{ PCI_VDEVICE(INTEL, 0x1f3e), board_ahci_avn }, /* Avoton RAID */
+	{ PCI_VDEVICE(INTEL, 0x1f3f), board_ahci_avn }, /* Avoton RAID */
 	{ PCI_VDEVICE(INTEL, 0x2823), board_ahci }, /* Wellsburg RAID */
 	{ PCI_VDEVICE(INTEL, 0x2827), board_ahci }, /* Wellsburg RAID */
 	{ PCI_VDEVICE(INTEL, 0x8d02), board_ahci }, /* Wellsburg AHCI */
@@ -675,6 +689,79 @@ static int ahci_p5wdh_hardreset(struct ata_link *link, unsigned int *class,
 	return rc;
 }
 
+/*
+ * ahci_avn_hardreset - attempt more aggressive recovery of Avoton ports.
+ *
+ * It has been observed with some SSDs that the timing of events in the
+ * link synchronization phase can leave the port in a state that can not
+ * be recovered by a SATA-hard-reset alone.  The failing signature is
+ * SStatus.DET stuck at 1 ("Device presence detected but Phy
+ * communication not established").  It was found that unloading and
+ * reloading the driver when this problem occurs allows the drive
+ * connection to be recovered (DET advanced to 0x3).  The critical
+ * component of reloading the driver is that the port state machines are
+ * reset by bouncing "port enable" in the AHCI PCS configuration
+ * register.  So, reproduce that effect by bouncing a port whenever we
+ * see DET==1 after a reset.
+ */
+static int ahci_avn_hardreset(struct ata_link *link, unsigned int *class,
+			      unsigned long deadline)
+{
+	const unsigned long *timing = sata_ehc_deb_timing(&link->eh_context);
+	struct ata_port *ap = link->ap;
+	struct ahci_port_priv *pp = ap->private_data;
+	struct ahci_host_priv *hpriv = ap->host->private_data;
+	u8 *d2h_fis = pp->rx_fis + RX_FIS_D2H_REG;
+	unsigned long tmo = deadline - jiffies;
+	struct ata_taskfile tf;
+	bool online;
+	int rc, i;
+
+	DPRINTK("ENTER\n");
+
+	ahci_stop_engine(ap);
+
+	for (i = 0; i < 2; i++) {
+		u16 val;
+		u32 sstatus;
+		int port = ap->port_no;
+		struct ata_host *host = ap->host;
+		struct pci_dev *pdev = to_pci_dev(host->dev);
+
+		/* clear D2H reception area to properly wait for D2H FIS */
+		ata_tf_init(link->device, &tf);
+		tf.command = ATA_BUSY;
+		ata_tf_to_fis(&tf, 0, 0, d2h_fis);
+
+		rc = sata_link_hardreset(link, timing, deadline, &online,
+				ahci_check_ready);
+
+		if (sata_scr_read(link, SCR_STATUS, &sstatus) != 0 ||
+				(sstatus & 0xf) != 1)
+			break;
+
+		ata_link_printk(link, KERN_INFO, "avn bounce port%d\n",
+				port);
+
+		pci_read_config_word(pdev, 0x92, &val);
+		val &= ~(1 << port);
+		pci_write_config_word(pdev, 0x92, val);
+		ata_msleep(ap, 1000);
+		val |= 1 << port;
+		pci_write_config_word(pdev, 0x92, val);
+		deadline += tmo;
+	}
+
+	hpriv->start_engine(ap);
+
+	if (online)
+		*class = ahci_dev_classify(ap);
+
+	DPRINTK("EXIT, rc=%d, class=%u\n", rc, *class);
+	return rc;
+}
+
+
 #ifdef CONFIG_PM
 static int ahci_pci_device_suspend(struct pci_dev *pdev, pm_message_t mesg)
 {