lkml.org 
[lkml]   [2013]   [Jan]   [2]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH/RFC 4/4] common: dma-mapping: Move dma_common_*() to <linux/dma-mapping.h>
Hello,

On 12/28/2012 8:23 PM, Geert Uytterhoeven wrote:
> dma_common_mmap() and dma_common_get_sgtable() are defined in
> drivers/base/dma-mapping.c, and always compiled if CONFIG_HAS_DMA=y.
>
> However, their forward declarations and the inline functions defined on top
> of them (dma_mmap_attrs(), dma_mmap_coherent(), dma_mmap_writecombine(),
> dma_get_sgtable_attrs()), dma_get_sgtable()) are in
> <asm-generic/dma-mapping-common.h>, which is not included by all
> architectures supporting CONFIG_HAS_DMA=y. There exist no alternative
> implementations.
>
> Hence for e.g. m68k allmodconfig, I get:
>
> 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’
>
> To fix this
> - Move the forward declarations and inline definitions to
> <linux/dma-mapping.h>, so all CONFIG_HAS_DMA=y architectures can use
> them,
> - Replace the hard "BUG_ON(!ops)" checks for dma_map_ops by soft checks,
> so architectures can fall back to the common code by returning NULL
> from their get_dma_ops(). Note that there are no "BUG_ON(!ops)" checks
> in other functions in <asm-generic/dma-mapping-common.h>,
> - Make "struct dma_map_ops *ops" const while we're at it.

I think that more appropriate way of handling it is to avoid dma_map_ops
based
calls (those archs probably have some reasons why they don't use it at
all) and
provide static inline stubs which call dma_common_mmap and
dma_common_get_sgtable.

It is definitely my fault that I missed the case of non-dma-map-ops
based archs
while I was adding support for dma_mmap_coherent and dma_get_sgt calls...

> (snipped)

Best regards
--
Marek Szyprowski
Samsung Poland R&D Center


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2013-01-02 16:01    [W:0.103 / U:0.212 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site