# Re: \[PATCH\] Sam440ep support

- From: Gerhard Pircher \<hidden\>
- Date: 2008-05-06 09:16:24 
- List: linuxppc-dev
- Page: https://ratatoskr.run/linuxppc-dev/2008/05/9439769
- Thread: https://ratatoskr.run/linuxppc-dev/2008/05/9439728/t.md

```text

-------- Original-Nachricht --------
> Datum: Tue, 06 May 2008 18:48:39 +1000
> Von: Benjamin Herrenschmidt [ref]
> An: Gerhard Pircher [ref]
> CC: <redacted>, Takashi Iwai <redacted>, <redacted>, <redacted>
> Betreff: Re: [PATCH] Sam440ep support

> 
> On Tue, 2008-05-06 at 09:51 +0200, Gerhard Pircher wrote:
> > Takashi Iwai posted a preliminary patch a long time ago. I tested it
> > on my machine and it failed with non coherent scatter-gather DMA
> > allocations (I guess almost all ALSA PCI drivers use SG DMA?).
> 
> How does Alsa allocate such SG ?
I can't answer this question. *ducked* :-) Takashi?

FYI: I posted the results of the test with Takashi's dma_mmap_coherent
patch here:
http://ozlabs.org/pipermail/linuxppc-dev/2006-June/024078.html

On the other side it looks like this problem does not only affect ALSA.
As far as I can tell also some V4L(2) drivers have a problem with mmaping
non coherent DMA allocations, but I'm not sure (it's a long time since I
did some tests with video cards on my AmigaOne).

Naturally I can do some tests, if you or Takashi come up with a new
patch.

Thanks!

Gerhard

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```