[alsa-devel] Allocating DMA buffer for non-PCM

Adrian Knoth adi at drcomp.erfurt.thur.de
Thu Feb 14 18:52:51 CET 2013

On Thu, Feb 14, 2013 at 06:46:30PM +0100, Clemens Ladisch wrote:

> > Would you say that the following is the proper way to allocate a DMA
> > buffer used to hold level data?
> >
> > 	err = snd_dma_alloc_pages(SNDRV_DMA_TYPE_DEV_SG,
> > 			snd_dma_pci_data(hdspm->pci),
> > 			MADIFX_LEVEL_BUFFER_SIZE, &hdspm->dmaLevelBuffer);
> >
> >     hdspm->level_buffer = snd_sgbuf_get_ptr(&(hdspm->dmaLevelBuffer), 0);
> I don't see the code asking for the address of the second page, so I
> guess there isn't one.


Just to be sure: Takashi has recommended to use
(u32*)dmaLevelBuffer.area. Even in the case of SG buffers, is this
virtual address continuous and safe for memset?


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