[alsa-devel] mapping externally allocated Scatter Gather DMA buffers
abraham.manu at gmail.com
Tue Nov 9 14:45:33 CET 2010
On Tue, Nov 9, 2010 at 6:21 PM, Jaroslav Kysela <perex at perex.cz> wrote:
> On Tue, 9 Nov 2010, Manu Abraham wrote:
>> On Tue, Nov 9, 2010 at 5:31 PM, Jaroslav Kysela <perex at perex.cz> wrote:
>>> On Tue, 9 Nov 2010, Manu Abraham wrote:
>>>> testbox ~ # arecord -Dhw:2,0
>>>> Recording WAVE 'stdin' : Unsigned 8 bit, Rate 8000 Hz, Mono
>>>> Any idea, why saa7231_hw_params is not getting invoked ?
>>> Your hw probably does not support directly 8-bit sample at 8000Hz, one
>>> channel. Use 'plughw:2,0' device instead 'hw:2,0' to let alsa-lib do all
>>> stream format conversions.
>> That didn't make any difference at all.
> Check your code. You probably created wrong hw_ops, looking to your code:
> .buffer_bytes_max = 512 * 4096,
> .period_bytes_min = 8192,
> .period_bytes_max = 8192,
> .periods_min = 8192,
> .periods_max = 8192,
> It's definitely an empty configuration space.
> You have buffer_bytes_max 2097152, but restricted number of periods to 8192
> and period_bytes to 8192.
> 8192 * 8192 = 67108864 which is not less than 2097152 (and I'm not counting
> the bytes for channels and formats). Bingo, the ALSA PCM code does not know
> what to configure.
> Decrease periods_min and probably also periods_max.
oh ! The error message was really a weird one. I can say that the
hardware can do 192 audio frames in an interrupt, whatever the frame
size is. So, what periods and period_bytes should I describe in the
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