> On Fri, Dec 24, 2010 at 12:20:32AM +0100, Janusz Krzysztofik wrote:
> > The patch tries to implement a solution suggested by Russell King,
> >
http://lists.infradead.org/pipermail/linux-arm-kernel/2010-December
> >/035264.html. It is expected to solve video buffer allocation issues
> > for at least a few soc_camera I/O memory less host interface
> > drivers, designed around the videobuf_dma_contig layer, which
> > allocates video buffers using dma_alloc_coherent().
> >
> > Created against linux-2.6.37-rc5.
> >
> > Tested on ARM OMAP1 based Amstrad Delta with a WIP OMAP1 camera
> > patch, patterned upon two mach-mx3 machine types which already try
> > to use the dma_declare_coherent_memory() method for reserving a
> > region of system RAM preallocated with another
> > dma_alloc_coherent(). Compile tested for all modified files except
> > arch/sh/drivers/pci/fixups-dreamcast.c.
>
> Another note: with the pair of patches I've sent to the
> linux-arm-kernel list earlier today changing the DMA coherent
> allocator to steal memory from the system at boot.
>
> This means there's less need to pre-allocate DMA memory - if there's
> sufficient contiguous space in the DMA region to satisfy the
> allocation, then the allocation will succeed. It's also independent
> of the maximum page size from the kernel's memory allocators too.
>
> So I suspect that mach-mx3 (and others) no longer need to do their
> own pre-allocation anymore if both of these patches go in.
