[alsa-devel] What is exact definition of "normal/inverted" FSYNC signal polarity?

[Mark Brown]

On Mon, Aug 31, 2015 at 12:05:51PM -0700, Anatol Pomozov wrote:

> Thus "normal" FSYNC for this driver means that the frame (L channel)
> starts at rising edge of FSYNC (wm8731 datasheet calls it DACLRC).
> "inverted" means frame starts at the falling edge. It differs both
> from TegraX1 and rt5677 above.

> It looks like each driver uses its own definition of FSYNC polarity.
> To avoid compatibility problems between different codecs/socs there
> should be a clean definition of what is FSYNC polarity is. I would
> propose something simple like:
>     ****  "normal" FSYNC means frame starts at rising edge of FSYNC,
> and "inverted" frame starts at falling FSYNC edge ****
> i.e. the same as for 8731.

Right, the Tegra and Realtek drivers are buggy here - the wm8731
definition is the one that essentially everything is using.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 473 bytes
Desc: Digital signature
URL: <http://mailman.alsa-project.org/pipermail/alsa-devel/attachments/20150901/a841d737/attachment.sig>