On Jul 9, 2009, at 8:47 PM, FUJITA Tomonori wrote:
I'm trying to convert POWERPC to use asm-generic/dma-mapping-common.h.
POWERPC needs addr_needs_map() in struct dma_mapping_ops for SWIOTLB
support but I want to avoid add addr_needs_map() in struct
dma_map_ops. IIRC, you guys think it as a temporary solution and
That is correct - I was planning to update when the iotlb folks had
decided on a final scheme for this. We don't like the additional
indirection we're getting with the current implementation.
talked about defining something like struct dma_data. Then we could
struct dev_archdata {
...
struct dma_data *ddata;
};
or
struct dev_archdata {
...
struct dma_data ddata;
};
struct dma_data needs dma_direct_offset, iommu_table, dma_base, and
dma_window_size, anything else?
IIRC, what we had talked about was simpler - we talked about changing
the current dev_archdata from this:
struct dev_archdata {
struct device_node *of_node;
struct dma_mapping_ops *dma_ops;
void *dma_data;
};
to this:
struct dev_archdata {
struct device_node *of_node;
struct dma_mapping_ops *dma_ops;
unsigned long long dma_data;
#ifdef CONFIG_SWIOTLB
dma_addr_t max_direct_dma_addr;
#endif
};
Where max_direct_dma_addr is the address beyond which a specific
device must use swiotlb, and dma_data is the offset like it is now
(but wider on 32-bit systems than void *). I believe Ben had mentioned
wanting to make the max_direct_dma_addr part conditional so we don't
bloat archdata on platforms that don't ever bounce.
The change to the type of dma_data is actually in preparation for an
optimization I have planned for 64-bit PCI devices (and which probably
requires more discussion), so that doesn't need to happen now - just
leave it as a void *, and I can post a followup patch.
Let me know if I can help or do any testing - I've been meaning to
look into switching to dma_map_ops for a while now but it hasn't
managed to pop off my todo stack.
Cheers,
Becky
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