RE: Problems with dma_mmap_writecombine on mach-pxa

[Frank Buss]

Russell King <rmk+lkml@xxxxxxxxxxxxxxxx> wrote:

> Since we map the whole lot in one go, if you get one page, there's no
> reason why you shouldn't get the lot.  This is why I'm wondering if
> it has something to do with your other modifications.

my colleage has found the bug: in the function dma_mmap in 
arch/arm/mm/consistent.c the call to remap_pfn_range uses 
user_size in PAGE_SIZE units, but looks like it is expected 
in bytes. When using (user_size << PAGE_SHIFT), it works.

I don't know, where to fix it: Should the lower level calls 
get the size in bytes (most function arguments in Linux 
kernel sources are not commented), this means fixing the 
dma_mmap, or should PAGE_SIZE be used, then the lower level 
functions needs to be fixed.

-- 
Frank Buß, fb@xxxxxxxxxxxxx
http://www.frank-buss.de, http://www.it4-systems.de

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