Re: [PATCH] powerpc: Implement dma_mmap_coherent()

-------- Original-Nachricht --------

Datum: Fri, 25 Mar 2011 17:50:06 +1100
Von: Benjamin Herrenschmidt [off-list ref]
An: linuxppc-dev [off-list ref]
CC: Takashi Iwai <redacted>
Betreff: [PATCH] powerpc: Implement dma_mmap_coherent()

This is used by Alsa to mmap buffers allocated with dma_alloc_coherent()
into userspace. We need a special variant to handle machines with
non-coherent DMAs as those buffers have "special" virt addresses and
require non-cachable mappings

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---

Dunno if anybody with CONFIG_NOT_COHERENT_CACHE has some audio device
that uses dma buffers (ie not usb-audio) and wants to try that out...
should fix a long standing problem.

Compilation fails here with these error messages:

  CC      arch/powerpc/mm/dma-noncoherent.o
arch/powerpc/mm/dma-noncoherent.c: In function ‘__dma_get_coherent_pfn’:
arch/powerpc/mm/dma-noncoherent.c:413: error: invalid operands to binary >> (have ‘void *’ and ‘int’)
cc1: warnings being treated as errors
arch/powerpc/mm/dma-noncoherent.c:414: error: passing argument 2 of ‘pud_offset’ makes integer from pointer without a cast
arch/powerpc/mm/dma-noncoherent.c:415: error: passing argument 2 of ‘pmd_offset’ makes integer from pointer without a cast
arch/powerpc/mm/dma-noncoherent.c:416: error: invalid operands to binary >> (have ‘void *’ and ‘int’)
make[1]: *** [arch/powerpc/mm/dma-noncoherent.o] Fehler 1
make: *** [arch/powerpc/mm] Fehler 2

Anyway, it compiles with explicit type casts and I could test it on my
semi-noncoherent AmigaOne. So far it works just fine with the VIA onboard
sound and a Soundblaster Live PCI card.

Thanks a lot for the fix!

regards,
Gerhard

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On Thu, 2011-03-31 at 22:39 +0200, Gerhard Pircher wrote:

Anyway, it compiles with explicit type casts and I could test it on my
semi-noncoherent AmigaOne. So far it works just fine with the VIA
onboard
sound and a Soundblaster Live PCI card.

Thanks a lot for the fix!

Yes, the version I sent to Linus has that fixed, I forgot to send it to
the list also :-)

Cheers,
Ben.