1 files changed, 43 insertions, 2 deletions

diff --git a/drivers/ata/libata-sff.c b/drivers/ata/libata-sff.c
index f93dc029dfd..9a10cb055ac 100644
--- a/drivers/ata/libata-sff.c
+++ b/drivers/ata/libata-sff.c
@@ -52,6 +52,7 @@ const struct ata_port_operations ata_sff_port_ops = {
 	.softreset		= ata_sff_softreset,
 	.hardreset		= sata_sff_hardreset,
 	.postreset		= ata_sff_postreset,
+	.drain_fifo		= ata_sff_drain_fifo,
 	.error_handler		= ata_sff_error_handler,
 	.post_internal_cmd	= ata_sff_post_internal_cmd,
 
@@ -2199,6 +2200,39 @@ void ata_sff_postreset(struct ata_link *link, unsigned int *classes)
 EXPORT_SYMBOL_GPL(ata_sff_postreset);
 
 /**
+ *	ata_sff_drain_fifo - Stock FIFO drain logic for SFF controllers
+ *	@qc: command
+ *
+ *	Drain the FIFO and device of any stuck data following a command
+ *	failing to complete. In some cases this is neccessary before a
+ *	reset will recover the device.
+ *
+ */
+
+void ata_sff_drain_fifo(struct ata_queued_cmd *qc)
+{
+	int count;
+	struct ata_port *ap;
+
+	/* We only need to flush incoming data when a command was running */
+	if (qc == NULL || qc->dma_dir == DMA_TO_DEVICE)
+		return;
+
+	ap = qc->ap;
+	/* Drain up to 64K of data before we give up this recovery method */
+	for (count = 0; (ap->ops->sff_check_status(ap) & ATA_DRQ)
+						&& count < 32768; count++)
+		ioread16(ap->ioaddr.data_addr);
+
+	/* Can become DEBUG later */
+	if (count)
+		ata_port_printk(ap, KERN_DEBUG,
+			"drained %d bytes to clear DRQ.\n", count);
+
+}
+EXPORT_SYMBOL_GPL(ata_sff_drain_fifo);
+
+/**
  *	ata_sff_error_handler - Stock error handler for BMDMA controller
  *	@ap: port to handle error for
  *
@@ -2239,7 +2273,8 @@ void ata_sff_error_handler(struct ata_port *ap)
 		 * really a timeout event, adjust error mask and
 		 * cancel frozen state.
 		 */
-		if (qc->err_mask == AC_ERR_TIMEOUT && (host_stat & ATA_DMA_ERR)) {
+		if (qc->err_mask == AC_ERR_TIMEOUT
+						&& (host_stat & ATA_DMA_ERR)) {
 			qc->err_mask = AC_ERR_HOST_BUS;
 			thaw = 1;
 		}
@@ -2250,6 +2285,13 @@ void ata_sff_error_handler(struct ata_port *ap)
 	ata_sff_sync(ap);		/* FIXME: We don't need this */
 	ap->ops->sff_check_status(ap);
 	ap->ops->sff_irq_clear(ap);
+	/* We *MUST* do FIFO draining before we issue a reset as several
+	 * devices helpfully clear their internal state and will lock solid
+	 * if we touch the data port post reset. Pass qc in case anyone wants
+	 *  to do different PIO/DMA recovery or has per command fixups
+	 */
+	if (ap->ops->drain_fifo)
+		ap->ops->drain_fifo(qc);
 
 	spin_unlock_irqrestore(ap->lock, flags);
 
@@ -2959,4 +3001,3 @@ out:
 EXPORT_SYMBOL_GPL(ata_pci_sff_init_one);
 
 #endif /* CONFIG_PCI */
-