lkml.org 
[lkml]   [2009]   [May]   [18]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] asm-generic: add a dma-mapping.h file
Arnd Bergmann wrote:
> h8300 and m32r currently do not provide a DMA mapping API
> and therefore cannot use the ATA drivers. This adds a
> generic version of dma-mapping.h for architectures that
> have none or very minimal actual support for DMA in hardware
> and makes the two architectures use it.
>
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
> On Sunday 17 May 2009 20:05:54 Jeff Garzik wrote:
>
>> That's what needs to happen. We provide no-op functions for e.g. PCI
>> and x86 DMI, for platforms where this support does not exist.
>>
>> Pretty much all architectures support some form of ATA. m68k, m32r,
>> h8300 and microblaze all have IDE interface, which means that libata
>> needs to work on that platform.
>>
>> The only !ATA arch in the entire kernel is s390, AFAICT.
>
> m68k only defines NO_DMA for Sun3 and Dragonball. Sun3 does
> not have ATA, Dragonball could probably just enable HAS_DMA.
>
> ---
> arch/h8300/Kconfig | 2 +-
> arch/h8300/include/asm/dma-mapping.h | 1 +
> arch/m32r/Kconfig | 2 +-
> arch/m32r/include/asm/dma-mapping.h | 1 +
> include/asm-generic/dma-mapping.h | 399 ++++++++++++++++++++++++++++++++++
> 5 files changed, 403 insertions(+), 2 deletions(-)
> create mode 100644 arch/h8300/include/asm/dma-mapping.h
> create mode 100644 arch/m32r/include/asm/dma-mapping.h
> create mode 100644 include/asm-generic/dma-mapping.h

My main comment is a bit non-specific... I tend to think that all
no-dma platforms should provide an API whose implementation always
returns errors, e.g. an inlined version of dma-mapping-broken.h.

That sort of setup permits the compiler's dead code elimination to work
on these no-dma platforms, while not crapping up the libata code with a
bunch of ifdefs.

Jeff






\
 
 \ /
  Last update: 2009-05-19 00:59    [from the cache]
©2003-2011 Jasper Spaans