[alsa-devel] [PATCH v4 4/4] ASoC: SAMSUNG: Add I2S0 internal dma driver

Liam Girdwood lrg at ti.com
Mon Jul 4 11:44:49 CEST 2011

On 01/07/11 17:12, Mark Brown wrote:
> On Fri, Jul 01, 2011 at 03:50:35PM +0100, Liam Girdwood wrote:
>> On 01/07/11 02:48, Sangbeom Kim wrote:
>>> +       if (res >= snd_pcm_lib_buffer_bytes(substream))
>>> +               res = 0;
>> Is it likely that your DMA pointer will go beyond the buffer size ?
>> If this happens then I suspect you have something wrong in your DMA config ?
> This is actually quite common - the normal case where it happens is that
> the DMA controller reports one location beyond the last location it read
> so when it hits the end of the buffer you see it report just beyond the
> end of the buffer (which is hit quite often since this tends to also
> generate an interrupt which causes a pointer() query).  Replacing the
> check with an == should be enough for that, though.

I agree, but I think he should really also have a comment here stating this condition if it exists.


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