[alsa-devel] possible problem in s3c24xx-pcm.c in git-devel branch

christian pellegrin chripell at gmail.com
Thu Nov 13 16:40:03 CET 2008

On Thu, Nov 13, 2008 at 4:17 PM, Mark Brown <broonie at sirena.org.uk> wrote:
> On Thu, Nov 13, 2008 at 03:57:08PM +0100, christian pellegrin wrote:
>> but this really could be "playing with DMA" since I'm not sure why
>> there is a 1 (since min_period is 2 I would guess 2 is the right
>> value). Anyway with this change play and capture work well.
> See the commit log - the underlying DMA code restricts the number of
> buffers that can be queued up prior to the start of DMA.

AFAIK it's limited to 2 transfers, one loaded and one running. It
could beneficial to have more of them (so the DMA doesn't stop if one
interrupt is delayed for too much time). But I don't know if it's so
critical. A period (4k) with cd quality sound takes 23 ms to be
played. An embedded system not responding to irqs for all this time
probably has worse issues.

Christian Pellegrin, see http://www.evolware.org/chri/
"Real Programmers don't play tennis, or any other sport which requires
you to change clothes. Mountain climbing is OK, and Real Programmers
wear their climbing boots to work in case a mountain should suddenly
spring up in the middle of the computer room."

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