ide: fix pre-EIDE SWDMA support

If the word 62 is not defined use the word 52 to get SWDMA mask
in ide_get_mode_mask().

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

1 files changed, 15 insertions, 1 deletions

diff --git a/drivers/ide/ide-dma.c b/drivers/ide/ide-dma.c
index 85db8e85443a..e8c6e1ed497a 100644
--- a/drivers/ide/ide-dma.c
+++ b/drivers/ide/ide-dma.c
@@ -702,8 +702,22 @@ static unsigned int ide_get_mode_mask(ide_drive_t *drive, u8 base)
                         mask = id->dma_mword & hwif->mwdma_mask;
                 break;
         case XFER_SW_DMA_0:
-                if (id->field_valid & 2)
+                if (id->field_valid & 2) {
                         mask = id->dma_1word & hwif->swdma_mask;
+                } else if (id->tDMA) {
+                        /*
+                         * ide_fix_driveid() doesn't convert ->tDMA to the
+                         * CPU endianness so we need to do it here
+                         */
+                        u8 mode = le16_to_cpu(id->tDMA);
+
+                        /*
+                         * if the mode is valid convert it to the mask
+                         * (the maximum allowed mode is XFER_SW_DMA_2)
+                         */
+                        if (mode <= 2)
+                                mask = ((2 << mode) - 1) & hwif->swdma_mask;
+                }
                 break;
         default:
                 BUG();