RE: [PATCH 0/1] v4l: videobuf2: Add DMA pool allocator

[Jeongtae Park <jtp.park@samsung.com>]

Hi,

> -----Original Message-----
> From: linux-media-owner@vger.kernel.org [mailto:linux-media-
> owner@vger.kernel.org] On Behalf Of Marek Szyprowski
> Sent: Tuesday, January 18, 2011 12:48 AM
> To: 'Jeongtae Park'; linux-media@vger.kernel.org; linux-samsung-
> soc@vger.kernel.org
> Cc: k.debski@samsung.com; jaeryul.oh@samsung.com; jonghun.han@samsung.com;
> kgene.kim@samsung.com
> Subject: RE: [PATCH 0/1] v4l: videobuf2: Add DMA pool allocator
> 
> Hello,
> 
> On Thursday, December 30, 2010 5:55 AM Jeongtae Park wrote:
> 
> > The DMA pool allocator allocates a memory using dma_alloc_coherent(),
> > creates a pool using generic allocator in the initialization.
> > For every allocation requests, the allocator returns a part of its
> > memory pool using generic allocator instead of new memory allocation.
> >
> > This allocator used for devices have below limitations.
> > - the start address should be aligned
> > - the range of memory access limited to the offset from the start
> >   address (= the allocation address should be existed in a
> >   constant offset from the start address)
> > - the allocation address should be aligned
> >
> > I would be grateful for your comments.
> >
> > This patch series contains:
> >
> > [PATCH 1/1] v4l: videobuf2: Add DMA pool allocator
> >
> > Best regards,
> > Jeongtae Park
> >
> > Patch summary:
> >
> > Jeongtae Park (1):
> >       v4l: videobuf2: Add DMA pool allocator
> >
> >  drivers/media/video/Kconfig              |    7 +
> >  drivers/media/video/Makefile             |    1 +
> >  drivers/media/video/videobuf2-dma-pool.c |  310
> ++++++++++++++++++++++++++++++
> >  include/media/videobuf2-dma-pool.h       |   37 ++++
> >  4 files changed, 355 insertions(+), 0 deletions(-)
> >  create mode 100644 drivers/media/video/videobuf2-dma-pool.c
> >  create mode 100644 include/media/videobuf2-dma-pool.h
> 
> The code looks nice but I have one suggestion. This dma-pool memory
allocator
> make sense only for a s5p-mfc driver. All other drivers can use dma-contig
> vb2
> allocator directly. For this reason I suggest to move this allocator
directly
> to drivers/media/video/s5p-mfc/ directory.
>

Is it not possible that there is the device with above limitations or
constraints?
If it's possible, the dma-pool allocator can be useful, but currently this
allocator
is useful only for a s5p-mfc.
But, all other allocators of vb2 framework are drivers/media/video/
directory.
I'm not sure which position is right for dma-pool allocator.

Thanks for your comment.

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