On Friday 06 July 2007, Timur Tabi wrote:
> Arnd Bergmann wrote:
>
> > Not sure exactly what arm does here, but it sounds like you want
> > to call remap_pfn_range with the _PAGE_NO_CACHE bit set in the
> > protection flags, and _PAGE_GUARDED not set.
>
> I always have a hard time with these mapping functions. Is this right?
>
> vma->vm_page_prot = __pgprot((pgprot_val(vma->vm_page_prot) | _PAGE_NO_CACHE)
> &
> ~_PAGE_GUARDED));
>
> ret = remap_pfn_range(vma, vma->vm_start, runtime->dma_addr,
> runtime->dma_bytes,
> vma->vm_page_prot);
>
> Alternatively, could I use function snd_pcm_lib_mmap_iomem()
> (sound/core/pcm_native.c)?
> It looks like it does the right thing, although it doesn't unset the guarded
> bit. If
> that's wrong, I can submit a patch to unset that bit on PowerPC, but like I
> said, I can
> never quite get my head around this mapping stuff.
The guarded bit is disabled by default, so you don't need t remove it, so
the function you quoted should be alright for this purpose. Not sure if you
need the ioremap in there though.
Arnd <><
_______________________________________________
Linuxppc-dev mailing list
Linuxppc-dev@ozlabs.org
https://ozlabs.org/mailman/listinfo/linuxppc-dev
