[PATCH 2/2] parport_pc: set properly the dma_mask for parport_pc device

[Alan Cox <alan@lxorguk.ukuu.org.uk>]

From: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>

parport_pc_probe_port() creates the own 'parport_pc' device if the
device argument is NULL. Then parport_pc_probe_port() doesn't
initialize the dma_mask and coherent_dma_mask of the device and calls
dma_alloc_coherent with it. dma_alloc_coherent fails because
dma_alloc_coherent() doesn't accept the uninitialized dma_mask:

http://lkml.org/lkml/2009/6/16/150

Long ago, X86_32 and X86_64 had the own dma_alloc_coherent
implementations; X86_32 accepted a device having dma_mask that is not
initialized however X86_64 didn't. When we merged them, we chose to
prohibit a device having dma_mask that is not initialized. I think
that it's good to require drivers to set up dma_mask (and
coherent_dma_mask) properly if the drivers want DMA.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Reported-by: Malcom Blaney <malcolm.blaney@maptek.com.au>
Tested-by: Malcom Blaney <malcolm.blaney@maptek.com.au>
Cc: stable@kernel.org
Signed-off-by: Alan Cox <alan@linux.intel.com>
---

 drivers/parport/parport_pc.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)


diff --git a/drivers/parport/parport_pc.c b/drivers/parport/parport_pc.c
index 7f1cca7..1032d5f 100644
--- a/drivers/parport/parport_pc.c
+++ b/drivers/parport/parport_pc.c
@@ -2290,6 +2290,9 @@ struct parport *parport_pc_probe_port(unsigned long int base,
 		if (IS_ERR(pdev))
 			return NULL;
 		dev = &pdev->dev;
+
+		dev->coherent_dma_mask = DMA_BIT_MASK(24);
+		dev->dma_mask = &dev->coherent_dma_mask;
 	}
 
 	ops = kmalloc(sizeof(struct parport_operations), GFP_KERNEL);