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>

2 files changed, 8 insertions, 0 deletions

diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 8824c8da3f2f..82af7011f2dd 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -2158,6 +2158,10 @@ retry:
 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 */
         { }
 };
diff --git a/include/linux/libata.h b/include/linux/libata.h
index 507f53ef8038..f5441edee55f 100644
--- a/include/linux/libata.h
+++ b/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 */