Re: [PATCH - v1] V4L-Fix videobuf_dma_contig_user_get() for non-aligned offsets

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On Wed, Dec 9, 2009 at 6:36 AM,  <m-karicheri2@xxxxxx> wrote:
> From: Muralidharan Karicheri <m-karicheri2@xxxxxx>
>
> If a USERPTR address that is not aligned to page boundary is passed to the
> videobuf_dma_contig_user_get() function, it saves a page aligned address to
> the dma_handle. This is not correct. This issue is observed when using USERPTR
> IO machism for buffer exchange.
>
> Updates from last version:-
>
> Adding offset for size calculation as per comment from Magnus Damm. This
> ensures the last page is also included for checking if memory is
> contiguous.
>
> Signed-off-by: Muralidharan Karicheri <m-karicheri2@xxxxxx>

Hi Murali,

I've spent some time testing this patch with the SuperH CEU driver in
USERPTR mode. My test case is based on capture.c with places a bunch
of QVGA frames directly after each other. The size of each QVGA frame
is not an even multiple of 4k page size, so some of the frames will
use a non-aligned start addresses. Currently the CEU driver page
aligns the size of each frame, but I'll fix that in an upcoming patch.
Thank you!

Acked-by: Magnus Damm <damm@xxxxxxxxxxxxx>
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