On Mon, May 11, 2015 at 9:30 AM, Konrad Rzeszutek Wilk
<konrad.wilk@xxxxxxxxxx> wrote:
> On Thu, May 07, 2015 at 10:19:05AM -0500, Bjorn Helgaas wrote:
>> [+cc Dave for sparc64, Yinghai]
>>
>> On Fri, May 01, 2015 at 01:32:15PM -0500, wdavis@xxxxxxxxxx wrote:
>> > From: Will Davis <wdavis@xxxxxxxxxx>
>> >
>> > Simply route these through to the new dma_(un)map_resource APIs.
>> >
>> > Signed-off-by: Will Davis <wdavis@xxxxxxxxxx>
>> > Reviewed-by: Terence Ripperda <tripperda@xxxxxxxxxx>
>> > Reviewed-by: John Hubbard <jhubbard@xxxxxxxxxx>
>> > ---
>> > include/asm-generic/pci-dma-compat.h | 14 ++++++++++++++
>> > 1 file changed, 14 insertions(+)
>> >
>> > diff --git a/include/asm-generic/pci-dma-compat.h b/include/asm-generic/pci-dma-compat.h
>> > index c110843..ac4a4ad 100644
>> > --- a/include/asm-generic/pci-dma-compat.h
>> > +++ b/include/asm-generic/pci-dma-compat.h
>> > @@ -61,6 +61,20 @@ pci_unmap_page(struct pci_dev *hwdev, dma_addr_t dma_address,
>> > dma_unmap_page(hwdev == NULL ? NULL : &hwdev->dev, dma_address, size, (enum dma_data_direction)direction);
>> > }
>> >
>> > +static inline dma_addr_t
>> > +pci_map_resource(struct pci_dev *hwdev, struct resource *resource,
>> > + unsigned long offset, size_t size, int direction)
>> > +{
>> > + return dma_map_resource(hwdev == NULL ? NULL : &hwdev->dev, resource, offset, size, (enum dma_data_direction)direction);
>> > +}
>>
>> On sparc64, PCI bus addresses, e.g., raw BAR values, can be 64 bits wide,
>> but dma_addr_t is only 32 bits [1]. So dma_addr_t is a bit of a problem
>> here. It's likely that we will add a pci_bus_addr_t, but that hasn't
>> happened yet [2].
>
> Why not just expand the 'dma_addr_t' to be unsigned long (if to support
> the T5-8 box)?
That would work, but would increase the kernel memory footprint [3].
I don't have numbers (maybe Dave does), but if it is really
significant, other platforms with IOMMUs might want to explore using a
dma_addr_t smaller than 64 bits, too.
>> [1] http://lkml.kernel.org/r/20150327.145016.86183910134380870.davem@xxxxxxxxxxxxx
>> [2] http://lkml.kernel.org/r/1427857069-6789-2-git-send-email-yinghai@xxxxxxxxxx
[3] http://lkml.kernel.org/r/20150403.124855.96516097693494126.davem@xxxxxxxxxxxxx
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