[alsa-devel] [PATCH] [RFC] ASoC: OMAP: fix OMAP1510 broken PCM pointer callback

[Jarkko Nikula]

On Mon, 29 Jun 2009 09:37:58 +0300
Peter Ujfalusi <peter.ujfalusi at nokia.com> wrote:

> Hmmm, I had taken a look at the 2.4.21 kernel sources, which I have
> laying around in my disk from an old project which used OMAP1510. The
> OSS audio code does use the CPC register for determining the DMA
> progress both for playback and recording. I know that the audio was
> working OK on that board, since we had doom running there.
> The difference that I can see is that the OSS code also configured
> the CCR:SYNC(4:0) bits as well.
> Looking at the DMA_CPC register description in the OMAP1510 TRM: it
> list two cases on how it behaves and both require the DMA_CCR:SYNC !=
> 0...
> 
> The current DMA code for OMAP1510 just plain ignores the DMA_CCR:SYNC
> for some reason.
> Can you try the following patch:
> 
> iff --git a/arch/arm/plat-omap/dma.c b/arch/arm/plat-omap/dma.c
> index 7fc8c04..38874e4 100644
> --- a/arch/arm/plat-omap/dma.c
> +++ b/arch/arm/plat-omap/dma.c
> @@ -266,6 +266,8 @@ void omap_set_dma_transfer_params(int lch, int
> data_type, int elem_count,
>                 ccr &= ~(1 << 5);
>                 if (sync_mode == OMAP_DMA_SYNC_FRAME)
>                         ccr |= 1 << 5;
> +               if (dma_trigger)
> +                       ccr |= dma_trigger & 0x1f;
>                 dma_write(ccr, CCR(lch));
> 
>                 ccr = dma_read(CCR2(lch));
> 
> Than can you print out in case of playback both the destination and
> source addresses supplied to the DMA, than in the pointer callback
> also print out the value returned by the omap_get_dma_src_pos
> function to see if this actually helps?
> 
Thanks for info Peter. So, Mark, put the workaround patch and my
acked-by on hold until this is also tried.


-- 
Jarkko