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, 3 insertions, 2 deletions

diff --git a/drivers/ide/pci/amd74xx.c b/drivers/ide/pci/amd74xx.c
index a4336995a410..7989bdd842a2 100644
--- a/drivers/ide/pci/amd74xx.c
+++ b/drivers/ide/pci/amd74xx.c
@@ -304,8 +304,9 @@ static int amd74xx_ide_dma_check(ide_drive_t *drive)
         amd_set_drive(drive, speed);
 
         if (drive->autodma && (speed & XFER_MODE) != XFER_PIO)
-                return HWIF(drive)->ide_dma_on(drive);
-        return HWIF(drive)->ide_dma_off_quietly(drive);
+                return 0;
+
+        return -1;
 }
 
 /*