[PATCH v2 2/2] ata: Fix the dma state machine lockup for the IDENTIFY DEVICE PIO mode command.

[Suman Tripathi <stripathi@xxxxxxx>]

This patch fixes the dma state machine lockup due to the IDENTIFY DEVICE PIO mode command. The controller is unable to clear the BSY bit after receiving the PIO setup FIS and results the dma state machine to go into the CMFatalErrorUpdate state resulting in the dma state machine lockup.
---
 drivers/ata/ahci.h       |  3 +++
 drivers/ata/ahci_xgene.c | 17 +++--------------
 drivers/ata/libahci.c    | 34 ++++++++++++++++++++++++++++++++++
 3 files changed, 40 insertions(+), 14 deletions(-)

diff --git a/drivers/ata/ahci.h b/drivers/ata/ahci.h
index 3c1760e..a4dd567 100644
--- a/drivers/ata/ahci.h
+++ b/drivers/ata/ahci.h
@@ -237,6 +237,9 @@ enum {
 						        error-handling stage) */
 	AHCI_HFLAG_MULTI_MSI		= (1 << 16), /* multiple PCI MSIs */
 	AHCI_HFLAG_NO_DEVSLP		= (1 << 17), /* no device sleep */
+	AHCI_HFLAG_BROKEN_PIO_CMD	= (1 << 18), /* Some PIO cmd's
+							resulting in HBA
+							dma state lockup */

 	/* ap->flags bits */

diff --git a/drivers/ata/ahci_xgene.c b/drivers/ata/ahci_xgene.c
index 77c89bf..741d5c7 100644
--- a/drivers/ata/ahci_xgene.c
+++ b/drivers/ata/ahci_xgene.c
@@ -104,14 +104,12 @@ static int xgene_ahci_init_memram(struct xgene_ahci_context *ctx)
  * @id: data buffer
  *
  * This custom read ID function is required due to the fact that the HW
- * does not support DEVSLP and the controller state machine may get stuck
- * after processing the ID query command.
+ * does not support DEVSLP.
  */
 static unsigned int xgene_ahci_read_id(struct ata_device *dev,
 				       struct ata_taskfile *tf, u16 *id)
 {
 	u32 err_mask;
-	void __iomem *port_mmio = ahci_port_base(dev->link->ap);

 	err_mask = ata_do_dev_read_id(dev, tf, id);
 	if (err_mask)
@@ -133,16 +131,6 @@ static unsigned int xgene_ahci_read_id(struct ata_device *dev,
 	 */
 	id[ATA_ID_FEATURE_SUPP] &= ~(1 << 8);

-	/*
-	 * Due to HW errata, restart the port if no other command active.
-	 * Otherwise the controller may get stuck.
-	 */
-	if (!readl(port_mmio + PORT_CMD_ISSUE)) {
-		writel(PORT_CMD_FIS_RX, port_mmio + PORT_CMD);
-		readl(port_mmio + PORT_CMD);	/* Force a barrier */
-		writel(PORT_CMD_FIS_RX | PORT_CMD_START, port_mmio + PORT_CMD);
-		readl(port_mmio + PORT_CMD);	/* Force a barrier */
-	}
 	return 0;
 }

@@ -303,7 +291,8 @@ static struct ata_port_operations xgene_ahci_ops = {
 };

 static const struct ata_port_info xgene_ahci_port_info = {
-	AHCI_HFLAGS(AHCI_HFLAG_NO_PMP | AHCI_HFLAG_YES_NCQ),
+	AHCI_HFLAGS(AHCI_HFLAG_NO_PMP | AHCI_HFLAG_YES_NCQ |
+		    AHCI_HFLAG_BROKEN_PIO_CMD),
 	.flags = AHCI_FLAG_COMMON | ATA_FLAG_NCQ,
 	.pio_mask = ATA_PIO4,
 	.udma_mask = ATA_UDMA6,
diff --git a/drivers/ata/libahci.c b/drivers/ata/libahci.c
index 584da77..2f0daa3 100644
--- a/drivers/ata/libahci.c
+++ b/drivers/ata/libahci.c
@@ -1592,6 +1592,32 @@ static void ahci_fbs_dec_intr(struct ata_port *ap)
 		dev_err(ap->host->dev, "failed to clear device error\n");
 }

+int ahci_complete_pio_cmd(struct ata_port *ap, u32 cmd_done)
+{
+	struct ata_queued_cmd *qc;
+
+	while (cmd_done) {
+		unsigned int tag = __ffs(cmd_done);
+
+		qc = ata_qc_from_tag(ap, tag);
+		if (qc) {
+			/*
+			 * For the IDENTIFY DEVICE PIO command,
+			 * some controller's unable to clear the BSY bit after
+			 * receiving the PIO Setup FIS from device resulting
+			 * the DMA state to go into CMFatalErrorUpdate state.
+			 * So need to restart the dma engine to get the
+			 * controller out of this state.
+			 */
+			if (qc->tf.command == ATA_CMD_ID_ATA)
+				ahci_restart_engine(ap);
+		}
+		cmd_done &= ~(1 << tag);
+	}
+
+	return 0;
+}
+
 static void ahci_error_intr(struct ata_port *ap, u32 irq_stat)
 {
 	struct ahci_host_priv *hpriv = ap->host->private_data;
@@ -1778,6 +1804,14 @@ static void ahci_handle_port_interrupt(struct ata_port *ap,
 	}


+	/* Due to HW errata, some controllers need special handling
+	 * of the completion of some PIO commands.
+	 */
+	if (hpriv->flags & AHCI_HFLAG_BROKEN_PIO_CMD) {
+		u32 cmd_done = ap->qc_active ^ qc_active;
+		ahci_complete_pio_cmd(ap, cmd_done);
+	}
+
 	rc = ata_qc_complete_multiple(ap, qc_active);

 	/* while resetting, invalid completions are expected */
--
1.8.2.1

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