pata_via: Blacklist some combinations of Transcend Flash and via

Reported by Mikulas Patocka.

VIA VT82C586B + Transcend TS64GSSD25-M v0826 does not work in UDMA mode

Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

drivers/ata/pata_via.c

@@ -336,6 +336,32 @@ static void via_set_dmamode(struct ata_port *ap, struct ata_device *adev)
 	via_do_set_mode(ap, adev, adev->dma_mode, tclock[mode], set_ast, udma[mode]);
 }
 
+/**
+ *	via_mode_filter		-	filter buggy device/mode pairs
+ *	@dev: ATA device
+ *	@mask: Mode bitmask
+ *
+ *	We need to apply some minimal filtering for old controllers and at least
+ *	one breed of Transcend SSD. Return the updated mask.
+ */
+
+static unsigned long via_mode_filter(struct ata_device *dev, unsigned long mask)
+{
+	struct ata_host *host = dev->link->ap->host;
+	const struct via_isa_bridge *config = host->private_data;
+	unsigned char model_num[ATA_ID_PROD_LEN + 1];
+
+	if (config->id == PCI_DEVICE_ID_VIA_82C586_0) {
+		ata_id_c_string(dev->id, model_num, ATA_ID_PROD, sizeof(model_num));
+		if (strcmp(model_num, "TS64GSSD25-M") == 0) {
+			ata_dev_printk(dev, KERN_WARNING,
+	"disabling UDMA mode due to reported lockups with this device.\n");
+			mask &= ~ ATA_MASK_UDMA;
+		}
+	}
+	return ata_bmdma_mode_filter(dev, mask);
+}
+
 /**
  *	via_tf_load - send taskfile registers to host controller
  *	@ap: Port to which output is sent
@@ -427,6 +453,7 @@ static struct ata_port_operations via_port_ops = {
 	.prereset	= via_pre_reset,
 	.sff_tf_load	= via_tf_load,
 	.port_start	= via_port_start,
+	.mode_filter	= via_mode_filter,
 };
 
 static struct ata_port_operations via_port_ops_noirq = {