[PATCH] libata: Simplex and other mode filtering logic

Add a field to the host_set called 'flags' (was host_set_flags changed
to suit Jeff)
Add a simplex_claimed field so we can remember who owns the DMA channel
Add a ->mode_filter() hook to allow drivers to filter modes
Add docs for mode_filter and set_mode
Filter according to simplex state
Filter cable in core

This provides the needed framework to support all the mode rules found
in the PATA world. The simplex filter deals with 'to spec' simplex DMA
systems found in older chips. The cable filter avoids duplicating the
same rules in each chip driver with PATA. Finally the mode filter is
neccessary because drive/chip combinations have errata that forbid
certain modes with some drives or types of ATA object.

Drive speed setup remains per channel for now and the filters now use
the framework Tejun put into place which cleans them up a lot from the
older libata-pata patches.

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

1 files changed, 29 insertions, 2 deletions

diff --git a/drivers/scsi/libata-core.c b/drivers/scsi/libata-core.c
index 41659448a2040c..b1ddf40533b573 100644
--- a/drivers/scsi/libata-core.c
+++ b/drivers/scsi/libata-core.c
@@ -1818,7 +1818,7 @@ static void ata_host_set_dma(struct ata_port *ap)
  */
 static void ata_set_mode(struct ata_port *ap)
 {
-	int i, rc;
+	int i, rc, used_dma = 0;
 
 	/* step 1: calculate xfer_mask */
 	for (i = 0; i < ATA_MAX_DEVICES; i++) {
@@ -1836,6 +1836,9 @@ static void ata_set_mode(struct ata_port *ap)
 		dma_mask = ata_pack_xfermask(0, dev->mwdma_mask, dev->udma_mask);
 		dev->pio_mode = ata_xfer_mask2mode(pio_mask);
 		dev->dma_mode = ata_xfer_mask2mode(dma_mask);
+
+		if (dev->dma_mode)
+			used_dma = 1;
 	}
 
 	/* step 2: always set host PIO timings */
@@ -1857,6 +1860,17 @@ static void ata_set_mode(struct ata_port *ap)
 			goto err_out;
 	}
 
+	/*
+	 *	Record simplex status. If we selected DMA then the other
+	 *	host channels are not permitted to do so.
+	 */
+
+	if (used_dma && (ap->host_set->flags & ATA_HOST_SIMPLEX))
+		ap->host_set->simplex_claimed = 1;
+
+	/*
+	 *	Chip specific finalisation
+	 */
 	if (ap->ops->post_set_mode)
 		ap->ops->post_set_mode(ap);
 
@@ -2646,13 +2660,14 @@ static int ata_dma_blacklisted(const struct ata_device *dev)
  */
 static void ata_dev_xfermask(struct ata_port *ap, struct ata_device *dev)
 {
+	struct ata_host_set *hs = ap->host_set;
 	unsigned long xfer_mask;
 	int i;
 
 	xfer_mask = ata_pack_xfermask(ap->pio_mask, ap->mwdma_mask,
 				      ap->udma_mask);
 
-	/* use port-wide xfermask for now */
+	/* FIXME: Use port-wide xfermask for now */
 	for (i = 0; i < ATA_MAX_DEVICES; i++) {
 		struct ata_device *d = &ap->device[i];
 		if (!ata_dev_present(d))
@@ -2662,12 +2677,23 @@ static void ata_dev_xfermask(struct ata_port *ap, struct ata_device *dev)
 		xfer_mask &= ata_id_xfermask(d->id);
 		if (ata_dma_blacklisted(d))
 			xfer_mask &= ~(ATA_MASK_MWDMA | ATA_MASK_UDMA);
+		/* Apply cable rule here. Don't apply it early because when
+		   we handle hot plug the cable type can itself change */
+		if (ap->cbl == ATA_CBL_PATA40)
+			xfer_mask &= ~(0xF8 << ATA_SHIFT_UDMA);
 	}
 
 	if (ata_dma_blacklisted(dev))
 		printk(KERN_WARNING "ata%u: dev %u is on DMA blacklist, "
 		       "disabling DMA\n", ap->id, dev->devno);
 
+	if (hs->flags & ATA_HOST_SIMPLEX) {
+		if (hs->simplex_claimed)
+			xfer_mask &= ~(ATA_MASK_MWDMA | ATA_MASK_UDMA);
+	}
+	if (ap->ops->mode_filter)
+		xfer_mask = ap->ops->mode_filter(ap, dev, xfer_mask);
+
 	ata_unpack_xfermask(xfer_mask, &dev->pio_mask, &dev->mwdma_mask,
 			    &dev->udma_mask);
 }
@@ -4531,6 +4557,7 @@ int ata_device_add(const struct ata_probe_ent *ent)
 	host_set->mmio_base = ent->mmio_base;
 	host_set->private_data = ent->private_data;
 	host_set->ops = ent->port_ops;
+	host_set->flags = ent->host_set_flags;
 
 	/* register each port bound to this device */
 	for (i = 0; i < ent->n_ports; i++) {