On Sun, Jan 13, 2013 at 12:36 PM, James Bottomley
<James.Bottomley@xxxxxxxxxxxxxxxxxxxxx> wrote:
> On Sun, 2013-01-13 at 11:44 +0100, Geert Uytterhoeven wrote:
>> parisc/allmodconfig:
>>
>> drivers/media/v4l2-core/videobuf2-dma-contig.c: In function ‘vb2_dc_mmap’:
>> drivers/media/v4l2-core/videobuf2-dma-contig.c:204: error: implicit declaration of function ‘dma_mmap_coherent’
>> drivers/media/v4l2-core/videobuf2-dma-contig.c: In function ‘vb2_dc_get_base_sgt’:
>> drivers/media/v4l2-core/videobuf2-dma-contig.c:387: error: implicit declaration of function ‘dma_get_sgtable’
>>
>> For architectures using dma_map_ops, dma_mmap_coherent() and
>> dma_get_sgtable() are provided in <asm-generic/dma-mapping-common.h>.
>>
>> Parisc does not use dma_map_ops, hence it should implement them as inline
>> stubs using dma_common_mmap() and dma_common_get_sgtable().
>>
>> Signed-off-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
>> Cc: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
>> Cc: linux-parisc@xxxxxxxxxxxxxxx
>> ---
>> arch/parisc/include/asm/dma-mapping.h | 10 ++++++++++
>> 1 files changed, 10 insertions(+), 0 deletions(-)
>>
>> diff --git a/arch/parisc/include/asm/dma-mapping.h b/arch/parisc/include/asm/dma-mapping.h
>> index 467bbd5..1fac0bf 100644
>> --- a/arch/parisc/include/asm/dma-mapping.h
>> +++ b/arch/parisc/include/asm/dma-mapping.h
>> @@ -238,4 +238,14 @@ void * sba_get_iommu(struct parisc_device *dev);
>> /* At the moment, we panic on error for IOMMU resource exaustion */
>> #define dma_mapping_error(dev, x) 0
>>
>> +/* drivers/base/dma-mapping.c */
>> +extern int dma_common_mmap(struct device *dev, struct vm_area_struct *vma,
>> + void *cpu_addr, dma_addr_t dma_addr, size_t size);
>> +extern int dma_common_get_sgtable(struct device *dev, struct sg_table *sgt,
>> + void *cpu_addr, dma_addr_t dma_addr,
>> + size_t size);
>> +
>> +#define dma_mmap_coherent(d, v, c, h, s) dma_common_mmap(d, v, c, h, s)
>> +#define dma_get_sgtable(d, t, v, h, s) dma_common_get_sgtable(d, t, v, h, s)
>
> What is the documentation around these functions? The name sounds
> suspiciously like you want a mapping of a buffer coherent between kernel
> and user space, which doesn't seem possible for us given the API. We're
> a VIPT architecture, so the only way we can do this is to have the
> actual vma user space address be congruent with cpu_addr. How do we do
> that if the vma and kernel addresses are already fixed?
I was already afraid of this when seeing the "coherent" in the naming...
> In other words, either the interface is unusable by parisc, or the
> common code definitely won't work for us.
So you probably want a static inline function that returns -EINVAL for now?
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
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