[libata] sata_sx4: fixup interrupt handling

Issuing ATA_CMD_SET_FEATURES (0xef) times out because
pdc20621_interrupt ignores command completion since
ATA_TFLAG_POLLING flag is set.

This has already been fixed for sata_promise:

commit 51b94d2a5a90d4800e74d7348bcde098a28f4fb3
Author: Tejun Heo <[e-mail]>
Date: Fri Jun 8 13:46:55 2007 -0700

sata_promise: use TF interface for polling NODATA commands

Also, this patch includes Mikael's original patches:

http://marc.info/?l=linux-ide&m=121135828227724&w=2
http://marc.info/?l=linux-ide&m=121144512109826&w=2

Signed-off-by: Mikael Pettersson <[e-mail]>
Signed-off-by: David Milburn <[e-mail]>
Signed-off-by: Jeff Garzik <[e-mail]>

drivers/ata/sata_sx4.c

···
 static unsigned int pdc20621_qc_issue(struct ata_queued_cmd *qc)
 {
 	switch (qc->tf.protocol) {
-	case ATA_PROT_DMA:
 	case ATA_PROT_NODATA:
+		if (qc->tf.flags & ATA_TFLAG_POLLING)
+			break;
+		/*FALLTHROUGH*/
+	case ATA_PROT_DMA:
 		pdc20621_packet_start(qc);
 		return 0;
 
···
 
 static void pdc20621_irq_clear(struct ata_port *ap)
 {
-	struct ata_host *host = ap->host;
-	void __iomem *mmio = host->iomap[PDC_MMIO_BAR];
-
-	mmio += PDC_CHIP0_OFS;
-
-	readl(mmio + PDC_20621_SEQMASK);
+	ioread8(ap->ioaddr.status_addr);
 }
 
 static irqreturn_t pdc20621_interrupt(int irq, void *dev_instance)
···
 static void pdc_thaw(struct ata_port *ap)
 {
 	void __iomem *mmio = ap->ioaddr.cmd_addr;
-	void __iomem *mmio_base;
 	u32 tmp;
 
 	/* FIXME: start HDMA engine, if zero ATA engines running */
 
-	/* reading SEQ mask register clears IRQ */
-	mmio_base = ap->host->iomap[PDC_MMIO_BAR] + PDC_CHIP0_OFS;
-	readl(mmio_base + PDC_20621_SEQMASK);
+	/* clear IRQ */
+	ioread8(ap->ioaddr.status_addr);
 
 	/* turn IRQ back on */
 	tmp = readl(mmio + PDC_CTLSTAT);
···
 static void pdc_tf_load_mmio(struct ata_port *ap, const struct ata_taskfile *tf)
 {
 	WARN_ON(tf->protocol == ATA_PROT_DMA ||
-		tf->protocol == ATA_PROT_NODATA);
+		tf->protocol == ATAPI_PROT_DMA);
 	ata_sff_tf_load(ap, tf);
 }
 
···
 static void pdc_exec_command_mmio(struct ata_port *ap, const struct ata_taskfile *tf)
 {
 	WARN_ON(tf->protocol == ATA_PROT_DMA ||
-		tf->protocol == ATA_PROT_NODATA);
+		tf->protocol == ATAPI_PROT_DMA);
 	ata_sff_exec_command(ap, tf);
 }