2007-06-01 16:46:52

by Maximus

[permalink] [raw]
Subject: dma_alloc_coherent fails

Hi,
Am using a linux 2.6.19 kernel for arm. the dma_alloc_coherent
function call in the kernel for 38400 bytes fails.


Has anyone faced this problem before?.


What could be make dma_alloc_coherent to success sometimes and fail sometimes?.

Regards,
John


2007-06-01 21:31:48

by Russell King

[permalink] [raw]
Subject: Re: dma_alloc_coherent fails

On Fri, Jun 01, 2007 at 10:16:41PM +0530, Maximus wrote:
> Hi,
> Am using a linux 2.6.19 kernel for arm. the dma_alloc_coherent
> function call in the kernel for 38400 bytes fails.
>
> Has anyone faced this problem before?.
>
> What could be make dma_alloc_coherent to success sometimes and fail
> sometimes?.

Memory fragmentation. Large allocations (> 1 page) are always unreliable.

--
Russell King
Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/
maintainer of: