Re: Bugs in usb-skeleton.c??? :)

[Manuel Lauss]

On Thu, Jul 13, 2006 at 05:10:20PM +0400, Sergej Pupykin wrote:
>  >> Does kmalloc always allocate pages that can be used in DMA?
> 
>  AvdV> normally yes. HOWEVER....
> 
> I use sh4 cpu...

on SH-4 traditionally the whole memory space is mapped all the
time, so any space returned by kmalloc is DMA-able.
(I don't know if this applies to the SH-4A core, too)
 
>  AvdV> ..it is nicer to use the DMA allocation API (which internally may fall
>  AvdV> back to kmalloc etc), while kmalloc may work, it can be quite slow in
>  AvdV> how it's made to work. So it's just nicer to just use the DMA memory
>  AvdV> allocators... (see Documentation/DMA-API.txt file for a description of
>  AvdV> this)

agree

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