[2/4] dma-mapping: add get_required_mask if arch overrides default

From: Milton Miller <miltonm@bga.com>

If an architecture sets ARCH_HAS_DMA_GET_REQUIRED_MASK and has settable
dma_map_ops, the required mask may change by the ops implementation.
For example, a system that always has an mmu inline may only require 32
bits while a swiotlb would desire bits to cover all of memory.

Therefore add the field if the architecture does not use the generic
definition of dma_get_required_mask. The first use will by by powerpc.
Note that this does add some dependency on the order in which files are
visible here.

Signed-off-by:  Milton Miller <miltonm@bga.com>
Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com>
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-kernel@vger.kernel.org
Cc: benh@kernel.crashing.org
---
 include/linux/dma-mapping.h |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

On Fri, 24 Jun 2011 12:05:23 -0700
Nishanth Aravamudan <nacc@us.ibm.com> wrote:

> From: Milton Miller <miltonm@bga.com>
> 
> If an architecture sets ARCH_HAS_DMA_GET_REQUIRED_MASK and has settable
> dma_map_ops, the required mask may change by the ops implementation.
> For example, a system that always has an mmu inline may only require 32
> bits while a swiotlb would desire bits to cover all of memory.
> 
> Therefore add the field if the architecture does not use the generic
> definition of dma_get_required_mask. The first use will by by powerpc.
> Note that this does add some dependency on the order in which files are
> visible here.
> 
> Signed-off-by:  Milton Miller <miltonm@bga.com>
> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com>
> Cc: linuxppc-dev@lists.ozlabs.org
> Cc: linux-kernel@vger.kernel.org
> Cc: benh@kernel.crashing.org
> ---
>  include/linux/dma-mapping.h |    3 +++
>  1 files changed, 3 insertions(+), 0 deletions(-)
> 
> diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
> index ba8319a..d0e023b 100644
> --- a/include/linux/dma-mapping.h
> +++ b/include/linux/dma-mapping.h
> @@ -49,6 +49,9 @@ struct dma_map_ops {
>  	int (*mapping_error)(struct device *dev, dma_addr_t dma_addr);
>  	int (*dma_supported)(struct device *dev, u64 mask);
>  	int (*set_dma_mask)(struct device *dev, u64 mask);
> +#ifdef ARCH_HAS_DMA_GET_REQUIRED_MASK
> +	u64 (*get_required_mask)(struct device *dev);
> +#endif
>  	int is_phys;
>  };

If you add get_required_mask to dma_map_ops, we should clean up ia64
too and implement the generic proper version in
dma-mapping-common.h. Then we kill ARCH_HAS_DMA_GET_REQUIRED_MASK
ifdef hack. Otherwise, I don't think it makes sense to add this to
dma_map_ops.

On Wed, 2011-06-29 at 17:19 +0900, FUJITA Tomonori wrote:
> On Fri, 24 Jun 2011 12:05:23 -0700
> Nishanth Aravamudan <nacc@us.ibm.com> wrote:
> 
> > From: Milton Miller <miltonm@bga.com>
> > 
> > If an architecture sets ARCH_HAS_DMA_GET_REQUIRED_MASK and has settable
> > dma_map_ops, the required mask may change by the ops implementation.
> > For example, a system that always has an mmu inline may only require 32
> > bits while a swiotlb would desire bits to cover all of memory.
> > 
> > Therefore add the field if the architecture does not use the generic
> > definition of dma_get_required_mask. The first use will by by powerpc.
> > Note that this does add some dependency on the order in which files are
> > visible here.

 .../...

> If you add get_required_mask to dma_map_ops, we should clean up ia64
> too and implement the generic proper version in
> dma-mapping-common.h. Then we kill ARCH_HAS_DMA_GET_REQUIRED_MASK
> ifdef hack. Otherwise, I don't think it makes sense to add this to
> dma_map_ops.

In the meantime, can I have an ack so I can include this along with the
rest of Milton's patches ? It's been around for a while now :-)

I'm a bit late for producing a powerpc-next (due to travelling).

Cheers,
Ben.

Sorry for the late reply,

On Thu, 01 Sep 2011 15:35:11 +1000
Benjamin Herrenschmidt <benh@kernel.crashing.org> wrote:

> On Wed, 2011-06-29 at 17:19 +0900, FUJITA Tomonori wrote:
> > On Fri, 24 Jun 2011 12:05:23 -0700
> > Nishanth Aravamudan <nacc@us.ibm.com> wrote:
> > 
> > > From: Milton Miller <miltonm@bga.com>
> > > 
> > > If an architecture sets ARCH_HAS_DMA_GET_REQUIRED_MASK and has settable
> > > dma_map_ops, the required mask may change by the ops implementation.
> > > For example, a system that always has an mmu inline may only require 32
> > > bits while a swiotlb would desire bits to cover all of memory.
> > > 
> > > Therefore add the field if the architecture does not use the generic
> > > definition of dma_get_required_mask. The first use will by by powerpc.
> > > Note that this does add some dependency on the order in which files are
> > > visible here.
> 
>  .../...
> 
> > If you add get_required_mask to dma_map_ops, we should clean up ia64
> > too and implement the generic proper version in
> > dma-mapping-common.h. Then we kill ARCH_HAS_DMA_GET_REQUIRED_MASK
> > ifdef hack. Otherwise, I don't think it makes sense to add this to
> > dma_map_ops.
> 
> In the meantime, can I have an ack so I can include this along with the
> rest of Milton's patches ? It's been around for a while now :-)

Sure, we can clean up this later.

Thanks,