[PATCH v2] ata: pata_marvell: Check the 'bmdma_addr' beforing reading

[Zheyu Ma <zheyuma97@gmail.com>]

Before detecting the cable type on the dma bar, the driver should check
whether the 'bmdma_addr' is zero, which means the adapter does not
support DMA, otherwise we will get the following error:

[    5.146634] Bad IO access at port 0x1 (return inb(port))
[    5.147206] WARNING: CPU: 2 PID: 303 at lib/iomap.c:44 ioread8+0x4a/0x60
[    5.150856] RIP: 0010:ioread8+0x4a/0x60
[    5.160238] Call Trace:
[    5.160470]  <TASK>
[    5.160674]  marvell_cable_detect+0x6e/0xc0 [pata_marvell]
[    5.161728]  ata_eh_recover+0x3520/0x6cc0
[    5.168075]  ata_do_eh+0x49/0x3c0

Signed-off-by: Zheyu Ma <zheyuma97@gmail.com>
---Changes in v2:
    - Delete the useless 'else'
---
 drivers/ata/pata_marvell.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/ata/pata_marvell.c b/drivers/ata/pata_marvell.c
index 0c5a51970fbf..014ccb0f45dc 100644
--- a/drivers/ata/pata_marvell.c
+++ b/drivers/ata/pata_marvell.c
@@ -77,6 +77,8 @@ static int marvell_cable_detect(struct ata_port *ap)
 	switch(ap->port_no)
 	{
 	case 0:
+		if (!ap->ioaddr.bmdma_addr)
+			return ATA_CBL_PATA_UNK;
 		if (ioread8(ap->ioaddr.bmdma_addr + 1) & 1)
 			return ATA_CBL_PATA40;
 		return ATA_CBL_PATA80;
-- 
2.25.1