ide: relax DMA info validity checking

There are some broken devices that report multiple DMA xfer modes
enabled at once (ATA spec doesn't allow it) but otherwise work fine
with DMA so just delete ide_id_dma_bug().

[ As discovered by detective work by Frans and Bart, due to how
  handling of the ID block was handled before commit c419993
  ("ide-iops: only clear DMA words on setting DMA mode") this
  check was always seeing zeros in the fields or other similar
  garbage.  Therefore this check wasn't actually checking anything.
  Now that the tests actually check the real bits, all we see are
  devices that trigger the check yet work perfectly fine, therefore
  killing this useless check is the best thing to do. -DaveM ]

Reported-by: Frans Pop <elendil@planet.nl>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 0 insertions, 24 deletions

diff --git a/drivers/ide/ide-dma.c b/drivers/ide/ide-dma.c
index 219e6fb78dc6..ee58c88dee5a 100644
--- a/drivers/ide/ide-dma.c
+++ b/drivers/ide/ide-dma.c
@@ -361,9 +361,6 @@ static int ide_tune_dma(ide_drive_t *drive)
         if (__ide_dma_bad_drive(drive))
                 return 0;
 
-        if (ide_id_dma_bug(drive))
-                return 0;
-
         if (hwif->host_flags & IDE_HFLAG_TRUST_BIOS_FOR_DMA)
                 return config_drive_for_dma(drive);
 
@@ -394,24 +391,6 @@ static int ide_dma_check(ide_drive_t *drive)
         return -1;
 }
 
-int ide_id_dma_bug(ide_drive_t *drive)
-{
-        u16 *id = drive->id;
-
-        if (id[ATA_ID_FIELD_VALID] & 4) {
-                if ((id[ATA_ID_UDMA_MODES] >> 8) &&
-                    (id[ATA_ID_MWDMA_MODES] >> 8))
-                        goto err_out;
-        } else if ((id[ATA_ID_MWDMA_MODES] >> 8) &&
-                   (id[ATA_ID_SWDMA_MODES] >> 8))
-                goto err_out;
-
-        return 0;
-err_out:
-        printk(KERN_ERR "%s: bad DMA info in identify block\n", drive->name);
-        return 1;
-}
-
 int ide_set_dma(ide_drive_t *drive)
 {
         int rc;
diff --git a/drivers/ide/ide-iops.c b/drivers/ide/ide-iops.c
index fa047150a1c6..917186ec4966 100644
--- a/drivers/ide/ide-iops.c
+++ b/drivers/ide/ide-iops.c
@@ -329,9 +329,6 @@ int ide_driveid_update(ide_drive_t *drive)
 
         kfree(id);
 
-        if ((drive->dev_flags & IDE_DFLAG_USING_DMA) && ide_id_dma_bug(drive))
-                ide_dma_off(drive);
-
         return 1;
 out_err:
         if (rc == 2)