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>

1 files changed, 17 insertions, 0 deletions

diff --git a/drivers/ata/pata_ali.c b/drivers/ata/pata_ali.c
index d12f386c1507..62aa2f90329a 100644
--- a/drivers/ata/pata_ali.c
+++ b/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,