Re: [PATCH 3/6] dma-mapping: pci: add pci_(un)map_resource

[Bjorn Helgaas <bhelgaas@google.com>]

[+cc Dave for sparc64, Yinghai]

On Fri, May 01, 2015 at 01:32:15PM -0500, wdavis@nvidia.com wrote:
> From: Will Davis <wdavis@nvidia.com>
> 
> Simply route these through to the new dma_(un)map_resource APIs.
> 
> Signed-off-by: Will Davis <wdavis@nvidia.com>
> Reviewed-by: Terence Ripperda <tripperda@nvidia.com>
> Reviewed-by: John Hubbard <jhubbard@nvidia.com>
> ---
>  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].

We do have existing problems already, e.g,. pci_bus_address() returns a
dma_addr_t, so it has the same problem.  So I guess this is just a heads-up
that this needs to be fixed eventually.

Bjorn

[1] http://lkml.kernel.org/r/20150327.145016.86183910134380870.davem@davemloft.net
[2] http://lkml.kernel.org/r/1427857069-6789-2-git-send-email-yinghai@kernel.org