pata_ali: Lots of problems still showing up with small ATAPI DMA

Hopefully there is a better long term solution but for now lets favour
reliability.
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

drivers/ata/pata_ali.c

@@ -285,6 +285,21 @@ static void ali_lock_sectors(struct ata_device *adev)
 	adev->max_sectors = 255;
 }
 
+/**
+ *	ali_check_atapi_dma	-	DMA check for most ALi controllers
+ *	@adev: Device
+ *
+ *	Called to decide whether commands should be sent by DMA or PIO
+ */
+ 
+static int ali_check_atapi_dma(struct ata_queued_cmd *qc)
+{
+	/* If its not a media command, its not worth it */
+	if (qc->nbytes < 2048)
+		return -EOPNOTSUPP;
+	return 0;
+}
+
 static struct scsi_host_template ali_sht = {
 	.module			= THIS_MODULE,
 	.name			= DRV_NAME,
@@ -381,6 +396,7 @@ static struct ata_port_operations ali_c2_port_ops = {
 	.mode_filter	= ata_pci_default_filter,
 	.tf_load	= ata_tf_load,
 	.tf_read	= ata_tf_read,
+	.check_atapi_dma = ali_check_atapi_dma,
 	.check_status 	= ata_check_status,
 	.exec_command	= ata_exec_command,
 	.dev_select 	= ata_std_dev_select,
@@ -418,6 +434,7 @@ static struct ata_port_operations ali_c5_port_ops = {
 	.mode_filter	= ata_pci_default_filter,
 	.tf_load	= ata_tf_load,
 	.tf_read	= ata_tf_read,
+	.check_atapi_dma = ali_check_atapi_dma,
 	.check_status 	= ata_check_status,
 	.exec_command	= ata_exec_command,
 	.dev_select 	= ata_std_dev_select,