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    SubjectRe: is_device_dma_capable
    From
    Thanks Fujita, your patch worked a treat!

    2009/6/16 FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>:
    > On Tue, 16 Jun 2009 17:53:03 +0930
    > Malcom Blaney <malcolm.blaney@maptek.com.au> wrote:
    >
    >> Hi Fujita,
    >>
    >> 2009/6/16 FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>:
    >> > You use X86_32, right?
    >>
    >> I have CONFIG_X86_32=y in my config file.
    >>
    >> >
    >> > In 2.6.25, 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, I think.
    >> >
    >> > When we merged them, we chose to prohibit a device having dma_mask
    >> > that is not initialized. I'm not sure the DMA docs say this but IMO
    >> > it's good to require drivers to set up dma_mask (and
    >> > coherent_dma_mask) properly if the drivers want DMA.
    >> >
    >>
    >> If you could point me in the direction of how to set these values
    >> correctly, I would appreciate it.
    >
    > You hit the problem that a device that parport_pc_probe_port creates
    > but doesn't set up the dma_mask properly, right (I'm not familiar with
    > the driver at all so I might misunderstand something)?
    >
    > If so, I guess that the following patch works (only compile tested).
    >
    >
    > diff --git a/drivers/parport/parport_pc.c b/drivers/parport/parport_pc.c
    > index 151bf5b..1af57b7 100644
    > --- a/drivers/parport/parport_pc.c
    > +++ b/drivers/parport/parport_pc.c
    > @@ -2271,6 +2271,9 @@ 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);
    >
    --
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