[alsa-devel] [PATCH V2 2/3] add set_tdm_slot in tdm dai to define the relationship between audio channel and tdm slot

Barry Song 21cnbao at gmail.com
Mon Aug 31 05:14:54 CEST 2009

On Fri, Aug 28, 2009 at 8:42 PM, Mark
Brown<broonie at opensource.wolfsonmicro.com> wrote:
> On Thu, 2009-08-20 at 10:37 +0800, Barry Song wrote:
>> On Wed, Aug 19, 2009 at 7:34 PM, Mark
>> Brown<broonie at opensource.wolfsonmicro.com> wrote:
>> > Yup, that DSP mode with I2S like channel layout (does it also do TDM in
>> > I2S mode by any chance?).  Could you submit a version of your patch
>> > which uses the default TDM layout - an API to rewrite things is likely
>> > to be a separate API?
>> I don't know what is your exact meaning.  Do you mean I send a patch
>> whose tdm slot is not changed, then send a patch which change the tdm
>> slot?
> Send a patch that allows selection of the active slots without rewriting
Sorry. I am not sure about your meaning yet. The problem is the slot
order, the match between slot number and channel number, not only
which slot is active, and which is not active.

> Although thinking about it I'm not sure if the driver is actually
> implementing TDM or not - does the CPU actually get configured to stop
> driving the data line during an inactive slot (so something else can
> drive it) or is it simply sending zeros on those slots?

It's the later. The hardware signal is still active but no valid data
in inactive slot.

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