libata-sff: Reenable Port Multiplier after libata-sff remodeling.

Keep track of the link on the which the current request is in progress.
It allows support of links behind port multiplier.

Not all libata-sff is PMP compliant. Code for native BMDMA controller
does not take in accound PMP.

Tested on Marvell 7042 and Sil7526.
Signed-off-by: NGwendal Grignou <gwendal@google.com>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

drivers/ata/libata-sff.c

@@ -1045,7 +1045,8 @@ static void ata_hsm_qc_complete(struct ata_queued_cmd *qc, int in_wq)
 int ata_sff_hsm_move(struct ata_port *ap, struct ata_queued_cmd *qc,
 		     u8 status, int in_wq)
 {
-	struct ata_eh_info *ehi = &ap->link.eh_info;
+	struct ata_link *link = qc->dev->link;
+	struct ata_eh_info *ehi = &link->eh_info;
 	unsigned long flags = 0;
 	int poll_next;
 
@@ -1301,8 +1302,14 @@ int ata_sff_hsm_move(struct ata_port *ap, struct ata_queued_cmd *qc,
 }
 EXPORT_SYMBOL_GPL(ata_sff_hsm_move);
 
-void ata_sff_queue_pio_task(struct ata_port *ap, unsigned long delay)
+void ata_sff_queue_pio_task(struct ata_link *link, unsigned long delay)
 {
+	struct ata_port *ap = link->ap;
+
+	WARN_ON((ap->sff_pio_task_link != NULL) &&
+		(ap->sff_pio_task_link != link));
+	ap->sff_pio_task_link = link;
+
 	/* may fail if ata_sff_flush_pio_task() in progress */
 	queue_delayed_work(ata_sff_wq, &ap->sff_pio_task,
 			   msecs_to_jiffies(delay));
@@ -1324,14 +1331,18 @@ static void ata_sff_pio_task(struct work_struct *work)
 {
 	struct ata_port *ap =
 		container_of(work, struct ata_port, sff_pio_task.work);
+	struct ata_link *link = ap->sff_pio_task_link;
 	struct ata_queued_cmd *qc;
 	u8 status;
 	int poll_next;
 
+	BUG_ON(ap->sff_pio_task_link == NULL); 
 	/* qc can be NULL if timeout occurred */
-	qc = ata_qc_from_tag(ap, ap->link.active_tag);
-	if (!qc)
+	qc = ata_qc_from_tag(ap, link->active_tag);
+	if (!qc) {
+		ap->sff_pio_task_link = NULL;
 		return;
+	}
 
 fsm_start:
 	WARN_ON_ONCE(ap->hsm_task_state == HSM_ST_IDLE);
@@ -1348,11 +1359,16 @@ static void ata_sff_pio_task(struct work_struct *work)
 		msleep(2);
 		status = ata_sff_busy_wait(ap, ATA_BUSY, 10);
 		if (status & ATA_BUSY) {
-			ata_sff_queue_pio_task(ap, ATA_SHORT_PAUSE);
+			ata_sff_queue_pio_task(link, ATA_SHORT_PAUSE);
 			return;
 		}
 	}
 
+	/*
+	 * hsm_move() may trigger another command to be processed.
+	 * clean the link beforehand.
+	 */
+	ap->sff_pio_task_link = NULL;
 	/* move the HSM */
 	poll_next = ata_sff_hsm_move(ap, qc, status, 1);
 
@@ -1379,6 +1395,7 @@ static void ata_sff_pio_task(struct work_struct *work)
 unsigned int ata_sff_qc_issue(struct ata_queued_cmd *qc)
 {
 	struct ata_port *ap = qc->ap;
+	struct ata_link *link = qc->dev->link;
 
 	/* Use polling pio if the LLD doesn't handle
 	 * interrupt driven pio and atapi CDB interrupt.
@@ -1399,7 +1416,7 @@ unsigned int ata_sff_qc_issue(struct ata_queued_cmd *qc)
 		ap->hsm_task_state = HSM_ST_LAST;
 
 		if (qc->tf.flags & ATA_TFLAG_POLLING)
-			ata_sff_queue_pio_task(ap, 0);
+			ata_sff_queue_pio_task(link, 0);
 
 		break;
 
@@ -1412,7 +1429,7 @@ unsigned int ata_sff_qc_issue(struct ata_queued_cmd *qc)
 		if (qc->tf.flags & ATA_TFLAG_WRITE) {
 			/* PIO data out protocol */
 			ap->hsm_task_state = HSM_ST_FIRST;
-			ata_sff_queue_pio_task(ap, 0);
+			ata_sff_queue_pio_task(link, 0);
 
 			/* always send first data block using the
 			 * ata_sff_pio_task() codepath.
@@ -1422,7 +1439,7 @@ unsigned int ata_sff_qc_issue(struct ata_queued_cmd *qc)
 			ap->hsm_task_state = HSM_ST;
 
 			if (qc->tf.flags & ATA_TFLAG_POLLING)
-				ata_sff_queue_pio_task(ap, 0);
+				ata_sff_queue_pio_task(link, 0);
 
 			/* if polling, ata_sff_pio_task() handles the
 			 * rest.  otherwise, interrupt handler takes
@@ -1444,7 +1461,7 @@ unsigned int ata_sff_qc_issue(struct ata_queued_cmd *qc)
 		/* send cdb by polling if no cdb interrupt */
 		if ((!(qc->dev->flags & ATA_DFLAG_CDB_INTR)) ||
 		    (qc->tf.flags & ATA_TFLAG_POLLING))
-			ata_sff_queue_pio_task(ap, 0);
+			ata_sff_queue_pio_task(link, 0);
 		break;
 
 	default:
@@ -2737,6 +2754,7 @@ EXPORT_SYMBOL_GPL(ata_bmdma_dumb_qc_prep);
 unsigned int ata_bmdma_qc_issue(struct ata_queued_cmd *qc)
 {
 	struct ata_port *ap = qc->ap;
+	struct ata_link *link = qc->dev->link;
 
 	/* defer PIO handling to sff_qc_issue */
 	if (!ata_is_dma(qc->tf.protocol))
@@ -2765,7 +2783,7 @@ unsigned int ata_bmdma_qc_issue(struct ata_queued_cmd *qc)
 
 		/* send cdb by polling if no cdb interrupt */
 		if (!(qc->dev->flags & ATA_DFLAG_CDB_INTR))
-			ata_sff_queue_pio_task(ap, 0);
+			ata_sff_queue_pio_task(link, 0);
 		break;
 
 	default:

drivers/ata/sata_mv.c

@@ -2284,7 +2284,7 @@ static unsigned int mv_qc_issue_fis(struct ata_queued_cmd *qc)
 	}
 
 	if (qc->tf.flags & ATA_TFLAG_POLLING)
-		ata_sff_queue_pio_task(ap, 0);
+		ata_sff_queue_pio_task(link, 0);
 	return 0;
 }
 

include/linux/libata.h

@@ -724,6 +724,7 @@ struct ata_port {
 	struct ata_ioports	ioaddr;	/* ATA cmd/ctl/dma register blocks */
 	u8			ctl;	/* cache of ATA control register */
 	u8			last_ctl;	/* Cache last written value */
+	struct ata_link*	sff_pio_task_link; /* link currently used */
 	struct delayed_work	sff_pio_task;
 #ifdef CONFIG_ATA_BMDMA
 	struct ata_bmdma_prd	*bmdma_prd;	/* BMDMA SG list */
@@ -1595,7 +1596,7 @@ extern void ata_sff_irq_on(struct ata_port *ap);
 extern void ata_sff_irq_clear(struct ata_port *ap);
 extern int ata_sff_hsm_move(struct ata_port *ap, struct ata_queued_cmd *qc,
 			    u8 status, int in_wq);
-extern void ata_sff_queue_pio_task(struct ata_port *ap, unsigned long delay);
+extern void ata_sff_queue_pio_task(struct ata_link *link, unsigned long delay);
 extern unsigned int ata_sff_qc_issue(struct ata_queued_cmd *qc);
 extern bool ata_sff_qc_fill_rtf(struct ata_queued_cmd *qc);
 extern unsigned int ata_sff_port_intr(struct ata_port *ap,