[PATCH v2 1/7] ARM: mm: Introduce archdata.dma_pfn_offset

[Arnd Bergmann]

On Thursday 27 February 2014 16:17:46 Santosh Shilimkar wrote:
> From: Grygorii Strashko <grygorii.strashko at ti.com>
> 
> In most of cases DMA addresses can be performed using offset value of
>  Bus address space relatively to physical address space as following:
> 
> PFN->DMA:
>  __pfn_to_phys(pfn + [-]dma_pfn_offset)
> 
> DMA->PFN:
>  __phys_to_pfn(dma_addr) + [-]dma_pfn_offset
> 
> This patch introduces new field dma_pfn_offset in ARM dev_archdata
> structure which has to be filed per-device at arch init time
> (simplest way is to use Platform bus notifier to handle
> BUS_NOTIFY_ADD_DEVICE event) and updates DMA address translation
> routines in order to accommodate bus offset value by default.
> 
> Cc: Russell King <linux at arm.linux.org.uk>
> Cc: Arnd Bergmann <arnd at arndb.de>
> Cc: Olof Johansson <olof at lixom.net>
> Signed-off-by: Grygorii Strashko <grygorii.strashko at ti.com>
> Signed-off-by: Santosh Shilimkar <santosh.shilimkar at ti.com>

This was my suggestion, and the implementation is trivial, so

Acked-by: Arnd Bergmann <arnd at arndb.de>

This should be most of what LinusW needs to generalize the
mach-integrator PCI DMA mapping.