[alsa-devel] Where are dma interrupts handled in ASoC code?

[John Kacur]

On Fri, Nov 21, 2008 at 12:01 PM, Mark Brown <broonie at sirena.org.uk> wrote:
> On Fri, Nov 21, 2008 at 10:45:46AM +0100, John Kacur wrote:
>
>> Where are dma overflow interrupts handled? For example I don't see
>> this in sound/soc/s3c24xx-i2s.c
>
> The s3c24xx ASoC code doesn't interact with the DMA controller directly,
> it uses the DMA API exported by the arch/arm code to do that.
>

Ok, thanks, I found that s3c2410_dma_request registers 3c2410_dma_irq.
(in arch/arm/plat-s3c24xx/dma.c) I see other platforms like omap
register an interrupt handler in the pcm code when they do a dma
request.

My scenario is this, the dma controller will be writing to the i2s
transmission fifo register (called I2SxTXFDAT on my platform - Jade).
If an overflow occurs an interrupt is generated. Among other tasks my
interrupt handler will have to clear a status bit in an i2s register.
I was thinking I need to somehow have my interrupt handler in my pcm
code, although conceptually it seems like an i2s thing.

If you have any hints for how I should design / implement this it
would be appreciated. I read the documentation on-line
http://www.kernel.org/pub/linux/kernel/people/tiwai/docs/writing-an-alsa-driver/x779.htm
but it doesn't quite seem to match my scenario.

Thanks