[PATCH] ide: add missing validity checks for identify words 62 and 63

Check validity of identify words 62 and 63 before using them in
ide_get_mode_mask().

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

 drivers/ide/ide-dma.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

Index: b/drivers/ide/ide-dma.c
===================================================================
--- a/drivers/ide/ide-dma.c
+++ b/drivers/ide/ide-dma.c
@@ -731,10 +731,12 @@ static unsigned int ide_get_mode_mask(id
 			mask &= 0x07;
 		break;
 	case XFER_MW_DMA_0:
-		mask = id->dma_mword & hwif->mwdma_mask;
+		if (id->field_valid & 2)
+			mask = id->dma_mword & hwif->mwdma_mask;
 		break;
 	case XFER_SW_DMA_0:
-		mask = id->dma_1word & hwif->swdma_mask;
+		if (id->field_valid & 2)
+			mask = id->dma_1word & hwif->swdma_mask;
 		break;
 	default:
 		BUG();