ide: cleanup ide_set_dma()

* ->dma_off_quietly is always called before ide_set_dma()
  so the call can be moved inside ide_set_dma().

* ide_dma_check() doesn't touch hardware so ->dma_off_quietly
  call for 'rc == -1' case is redundant, remove it.

* '0' and '-1' are the only values returned by ide_dma_check()
  so remove dead code for other cases.

There should be no functionality changes caused by this patch.
Acked-by: NSergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: NBartlomiej Zolnierkiewicz <bzolnier@gmail.com>

drivers/ide/ide-dma.c

@@ -827,22 +827,19 @@ int ide_set_dma(ide_drive_t *drive)
 	ide_hwif_t *hwif = drive->hwif;
 	int rc;
 
-	rc = ide_dma_check(drive);
-
-	switch(rc) {
-	case -1: /* DMA needs to be disabled */
+	/*
+	 * Force DMAing for the beginning of the check.
+	 * Some chipsets appear to do interesting
+	 * things, if not checked and cleared.
+	 *   PARANOIA!!!
+	 */
 	hwif->dma_off_quietly(drive);
-		return -1;
-	case  0: /* DMA needs to be enabled */
-		return hwif->ide_dma_on(drive);
-	case  1: /* DMA setting cannot be changed */
-		break;
-	default:
-		BUG();
-		break;
-	}
 
+	rc = ide_dma_check(drive);
+	if (rc)
 		return rc;
+
+	return hwif->ide_dma_on(drive);
 }
 
 #ifdef CONFIG_BLK_DEV_IDEDMA_PCI

drivers/ide/ide-io.c

@@ -221,7 +221,6 @@ static ide_startstop_t ide_start_power_step(ide_drive_t *drive, struct request *
 		 */
 		if (drive->hwif->ide_dma_on == NULL)
 			break;
-		drive->hwif->dma_off_quietly(drive);
 		/*
 		 * TODO: respect ->using_dma setting
 		 */

drivers/ide/ide-probe.c

@@ -833,18 +833,10 @@ static void probe_hwif(ide_hwif_t *hwif)
 
 			drive->nice1 = 1;
 
-			if (hwif->ide_dma_on) {
-				/*
-				 * Force DMAing for the beginning of the check.
-				 * Some chipsets appear to do interesting
-				 * things, if not checked and cleared.
-				 *   PARANOIA!!!
-				 */
-				hwif->dma_off_quietly(drive);
+			if (hwif->ide_dma_on)
 				ide_set_dma(drive);
 		}
 	}
-	}
 
 	for (unit = 0; unit < MAX_DRIVES; ++unit) {
 		ide_drive_t *drive = &hwif->drives[unit];

drivers/ide/ide.c

@@ -851,7 +851,6 @@ int set_using_dma(ide_drive_t *drive, int arg)
 	err = 0;
 
 	if (arg) {
-		hwif->dma_off_quietly(drive);
 		if (ide_set_dma(drive))
 			err = -EIO;
 	} else