ide: add ide_set_dma() helper (v2)

* add ide_set_dma() helper and make ide_hwif_t.ide_dma_check return
  -1 when DMA needs to be disabled (== need to call ->ide_dma_off_quietly)
   0 when DMA needs to be enabled  (== need to call ->ide_dma_on)
   1 when DMA setting shouldn't be changed
* fix IDE code to use ide_set_dma() instead if using ->ide_dma_check directly

v2:
* updated for scc_pata

Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

1 files changed, 2 insertions, 4 deletions

diff --git a/drivers/ide/pci/serverworks.c b/drivers/ide/pci/serverworks.c
index f44a5ab8fe00..dbcd37a0c652 100644
--- a/drivers/ide/pci/serverworks.c
+++ b/drivers/ide/pci/serverworks.c
@@ -315,17 +315,15 @@ static int config_chipset_for_dma (ide_drive_t *drive)
 
 static int svwks_config_drive_xfer_rate (ide_drive_t *drive)
 {
-        ide_hwif_t *hwif        = HWIF(drive);
-
         drive->init_speed = 0;
 
         if (ide_use_dma(drive) && config_chipset_for_dma(drive))
-                return hwif->ide_dma_on(drive);
+                return 0;
 
         if (ide_use_fast_pio(drive))
                 config_chipset_for_pio(drive);
 
-        return hwif->ide_dma_off_quietly(drive);
+        return -1;
 }
 
 static unsigned int __devinit init_chipset_svwks (struct pci_dev *dev, const char *name)