libata: add whitelist for devices with known good pata-sata bridges

libata currently imposes a UDMA5 max transfer rate and 200 sector max
transfer size for SATA devices that sit behind a pata-sata bridge. Lots
of devices have known good bridges that don't need this limit applied.
The MTRON SSD disks are such devices. Transfer rates are increased by
20-30% with the restriction removed.

So add a "blacklist" entry for the MTRON devices, with a flag indicating
that the bridge is known good.
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

drivers/ata/libata-core.c

@@ -2158,6 +2158,10 @@ int ata_dev_read_id(struct ata_device *dev, unsigned int *p_class,
 static inline u8 ata_dev_knobble(struct ata_device *dev)
 {
 	struct ata_port *ap = dev->link->ap;
+
+	if (ata_dev_blacklisted(dev) & ATA_HORKAGE_BRIDGE_OK)
+		return 0;
+
 	return ((ap->cbl == ATA_CBL_SATA) && (!ata_id_is_sata(dev->id)));
 }
 
@@ -4062,6 +4066,9 @@ static const struct ata_blacklist_entry ata_device_blacklist [] = {
 	{ "TSSTcorp CDDVDW SH-S202N", "SB00",	  ATA_HORKAGE_IVB, },
 	{ "TSSTcorp CDDVDW SH-S202N", "SB01",	  ATA_HORKAGE_IVB, },
 
+	/* Devices that do not need bridging limits applied */
+	{ "MTRON MSP-SATA*",		NULL,	ATA_HORKAGE_BRIDGE_OK, },
+
 	/* End Marker */
 	{ }
 };

include/linux/libata.h

@@ -372,6 +372,7 @@ enum {
 	ATA_HORKAGE_IPM		= (1 << 7),	/* Link PM problems */
 	ATA_HORKAGE_IVB		= (1 << 8),	/* cbl det validity bit bugs */
 	ATA_HORKAGE_STUCK_ERR	= (1 << 9),	/* stuck ERR on next PACKET */
+	ATA_HORKAGE_BRIDGE_OK	= (1 << 10),	/* no bridge limits */
 
 	 /* DMA mask for user DMA control: User visible values; DO NOT
 	    renumber */