steven.zhang wrote:
So many thanks!Vladimir.
But why 720*480 succeeded?Its size is 2488320 byte, which exceeds 2M
already.
I have checked the CONSISTENT_DMA_SIZE of my arch.Its value is 14M, that
should be enough.
yes, I saw that after sending the mail
any other suggestion?
well, the kernel tries to find such a big contiguous piece of memory, maybe the
memory is already too fragmented at that time?
On Wed, 2008-05-07 at 09:31 +0200, Vladimir Pantelic wrote:
steven.zhang wrote:
> Hi, all.
> I am porting the davincifb driver to support 1280*720 resolution.
> As you know, I should alloc memory for different OSD windows.
> To support 1280*720 p, I do it as follows:
>
> #define DISP_XRES 1280
> #define DISP_YRES 720
> #define DISP_MEMY 740
> #define VID0_FB_SIZE (round_32(DISP_XRES*16/8) * DISP_MEMY * TRIPLE_BUF)
>
> using dma_alloc_coherent() to allocate 5683200byte
> memory.However, it fails.
> when define DISP_XRES be 720 and DISP_YRES be 480, it succeeds.
>
>
> What can be the problems? dma_alloc_coherent() can not allocate 5683200
> (about 5M) memory using for DMA?
maybe this:
http://kerneltrap.org/node/3600
what is your CONSISTENT_DMA_SIZE, default is:
/linux/include/asm/memory.h:
#define CONSISTENT_DMA_SIZE SZ_2M
but your arch could define another value.
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