libata: Fix a large collection of DMA mode mismatches

Dave Müller sent a diff for the pata_oldpiix that highlighted a problem
where a lot of the ATA drivers assume dma_mode == 0 means "no DMA" while
the core code uses 0xFF.

This turns out to have other consequences such as code doing >= XFER_UDMA_0
also catching 0xFF as UDMAlots. Fortunately it doesn't generally affect
set_dma_mode, although some drivers call back into their own set mode code
from other points.

Having been through the drivers I've added helpers for using_udma/using_mwdma
dma_enabled so that people don't open code ranges that may change (eg if UDMA8
appears somewhere)

Thanks to David for the initial bits
[and added fix for pata_oldpiix from and signed-off-by Dave Mueller
 <dave.mueller@gmx.ch>  -jg]

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/drivers/ata/pata_oldpiix.c b/drivers/ata/pata_oldpiix.c
index e678af383d13..df64f2443001 100644
--- a/drivers/ata/pata_oldpiix.c
+++ b/drivers/ata/pata_oldpiix.c
@@ -198,7 +198,7 @@ static unsigned int oldpiix_qc_issue(struct ata_queued_cmd *qc)
 
         if (adev != ap->private_data) {
                 oldpiix_set_piomode(ap, adev);
-                if (adev->dma_mode)
+                if (ata_dma_enabled(adev))
                         oldpiix_set_dmamode(ap, adev);
         }
         return ata_sff_qc_issue(qc);