ide: add IDE_HFLAG_SERIALIZE_DMA host flag

* Add IDE_HFLAG_SERIALIZE_DMA host flag to serialize ports
  if DMA is available and handle it in ide_init_port().

* Convert sl82c105 host driver to use this new flag.
Signed-off-by: NBartlomiej Zolnierkiewicz <bzolnier@gmail.com>

drivers/ide/ide-probe.c

@@ -1367,8 +1367,11 @@ static void ide_init_port(ide_hwif_t *hwif, unsigned int port,
 	if (hwif->chipset != ide_dtc2278 || hwif->channel == 0)
 		hwif->port_ops = d->port_ops;
 
-	if ((d->host_flags & IDE_HFLAG_SERIALIZE) && hwif->mate)
-		hwif->mate->serialized = hwif->serialized = 1;
+	if ((d->host_flags & IDE_HFLAG_SERIALIZE) ||
+	    ((d->host_flags & IDE_HFLAG_SERIALIZE_DMA) && hwif->dma_base)) {
+		if (hwif->mate)
+			hwif->mate->serialized = hwif->serialized = 1;
+	}
 
 	hwif->swdma_mask = d->swdma_mask;
 	hwif->mwdma_mask = d->mwdma_mask;

drivers/ide/pci/sl82c105.c

@@ -296,9 +296,6 @@ static void __devinit init_hwif_sl82c105(ide_hwif_t *hwif)
 	hwif->dma_start			= &sl82c105_dma_start;
 	hwif->ide_dma_end		= &sl82c105_dma_end;
 	hwif->dma_timeout		= &sl82c105_dma_timeout;
-
-	if (hwif->mate)
-		hwif->serialized = hwif->mate->serialized = 1;
 }
 
 static const struct ide_port_ops sl82c105_port_ops = {
@@ -319,6 +316,7 @@ static const struct ide_port_info sl82c105_chipset __devinitdata = {
 #if defined(CONFIG_LOPEC) || defined(CONFIG_SANDPOINT)
 			  IDE_HFLAG_FORCE_LEGACY_IRQS |
 #endif
+			  IDE_HFLAG_SERIALIZE_DMA |
 			  IDE_HFLAG_NO_AUTODMA,
 	.pio_mask	= ATA_PIO5,
 	.mwdma_mask	= ATA_MWDMA2,
@@ -338,6 +336,7 @@ static int __devinit sl82c105_init_one(struct pci_dev *dev, const struct pci_dev
 				 "revision %d, BM-DMA disabled\n", rev);
 		d.init_hwif = NULL;
 		d.mwdma_mask = 0;
+		d.host_flags &= ~IDE_HFLAG_SERIALIZE_DMA;
 	}
 
 	return ide_setup_pci_device(dev, &d);

include/linux/ide.h

@@ -1087,6 +1087,8 @@ enum {
 	/* unmask IRQs */
 	IDE_HFLAG_UNMASK_IRQS		= (1 << 25),
 	IDE_HFLAG_ABUSE_SET_DMA_MODE	= (1 << 26),
+	/* serialize ports if DMA is possible (for sl82c105) */
+	IDE_HFLAG_SERIALIZE_DMA		= (1 << 27),
 	/* force host out of "simplex" mode */
 	IDE_HFLAG_CLEAR_SIMPLEX		= (1 << 28),
 	/* DSC overlap is unsupported */