[PATCH] libata: set dma_mode to 0xff in reset

ata_device->dma_mode's initial value is zero, which is not a valid dma
mode, but ata_dma_enabled will return true for this value. This patch
sets dma_mode to 0xff in reset function, so that ata_dma_enabled will
not return true for this case, or it will cause problem for pata_acpi.

The corrsponding bugzilla page is at:
https://bugzilla.kernel.org/show_bug.cgi?id=49151

Reported-by: Phillip Wood <redacted>
Signed-off-by: Aaron Lu <redacted>
Tested-by: Szymon Janc <redacted>
Tested-by: Dutra Julio <redacted>
Cc: <stable@kernel.org>
---
 drivers/ata/libata-core.c | 1 +
 drivers/ata/libata-eh.c   | 1 +
 2 files changed, 2 insertions(+)

diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index f46fbd3..586362e 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c

@@ -2560,6 +2560,7 @@ int ata_bus_probe(struct ata_port *ap)
 		 * bus as we may be talking too fast.
 		 */
 		dev->pio_mode = XFER_PIO_0;
+		dev->dma_mode = 0xff;
 
 		/* If the controller has a pio mode setup function
 		 * then use it to set the chipset to rights. Don't

diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c
index e60437c..bf039b0 100644
--- a/drivers/ata/libata-eh.c
+++ b/drivers/ata/libata-eh.c

@@ -2657,6 +2657,7 @@ int ata_eh_reset(struct ata_link *link, int classify,
 		 * bus as we may be talking too fast.
 		 */
 		dev->pio_mode = XFER_PIO_0;
+		dev->dma_mode = 0xff;
 
 		/* If the controller has a pio mode setup function
 		 * then use it to set the chipset to rights. Don't

-- 
1.7.12.4