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, 30 insertions, 7 deletions

diff --git a/drivers/ide/ide-dma.c b/drivers/ide/ide-dma.c
index 1a288e5307d3..4fbcea4c1025 100644
--- a/drivers/ide/ide-dma.c
+++ b/drivers/ide/ide-dma.c
@@ -348,15 +348,14 @@ EXPORT_SYMBOL_GPL(ide_destroy_dmatable);
 static int config_drive_for_dma (ide_drive_t *drive)
 {
         struct hd_driveid *id = drive->id;
-        ide_hwif_t *hwif = HWIF(drive);
 
-        if ((id->capability & 1) && hwif->autodma) {
+        if ((id->capability & 1) && drive->hwif->autodma) {
                 /*
                  * Enable DMA on any drive that has
                  * UltraDMA (mode 0/1/2/3/4/5/6) enabled
                  */
                 if ((id->field_valid & 4) && ((id->dma_ultra >> 8) & 0x7f))
-                        return hwif->ide_dma_on(drive);
+                        return 0;
                 /*
                  * Enable DMA on any drive that has mode2 DMA
                  * (multi or single) enabled
@@ -364,14 +363,14 @@ static int config_drive_for_dma (ide_drive_t *drive)
                 if (id->field_valid & 2)        /* regular DMA */
                         if ((id->dma_mword & 0x404) == 0x404 ||
                             (id->dma_1word & 0x404) == 0x404)
-                                return hwif->ide_dma_on(drive);
+                                return 0;
 
                 /* Consult the list of known "good" drives */
                 if (__ide_dma_good_drive(drive))
-                        return hwif->ide_dma_on(drive);
+                        return 0;
         }
-//      if (hwif->tuneproc != NULL) hwif->tuneproc(drive, 255);
-        return hwif->ide_dma_off_quietly(drive);
+
+        return -1;
 }
 
 /**
@@ -765,6 +764,30 @@ bug_dma_off:
 
 EXPORT_SYMBOL(ide_dma_verbose);
 
+int ide_set_dma(ide_drive_t *drive)
+{
+        ide_hwif_t *hwif = drive->hwif;
+        int rc;
+
+        rc = hwif->ide_dma_check(drive);
+
+        switch(rc) {
+        case -1: /* DMA needs to be disabled */
+                return hwif->ide_dma_off_quietly(drive);
+        case  0: /* DMA needs to be enabled */
+                return hwif->ide_dma_on(drive);
+        case  1: /* DMA setting cannot be changed */
+                break;
+        default:
+                BUG();
+                break;
+        }
+
+        return rc;
+}
+
+EXPORT_SYMBOL_GPL(ide_set_dma);
+
 #ifdef CONFIG_BLK_DEV_IDEDMA_PCI
 int __ide_dma_lostirq (ide_drive_t *drive)
 {