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ASoC: rsnd: add detail explanation of L/R conversion timing 

Renesas Sound device *Hardware* L/R and Linux *Software* L/R are
inverted. Because of this background, it needs to convert L/R.
Then, DVC needs *Hardware* L/R, and Linux needs *Software* L/R.
Because Playback/Capture needs different timing, and there is no
explanation about it on source code / git log, this patch adds it.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
This commit is contained in:
Kuninori Morimoto 2017-06-09 00:34:09 +00:00 committed by Mark Brown
parent a97a06c7ef
commit 8cce431aa2
1 changed files with 18 additions and 0 deletions
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18
sound/soc/sh/rcar/core.c
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@ -310,6 +310,24 @@ u32 rsnd_get_dalign(struct rsnd_mod *mod, struct rsnd_dai_stream *io)
u32 val = 0x76543210;
u32 mask = ~0;
/*
* *Hardware* L/R and *Software* L/R are inverted.
* We need to care about inversion timing to control
* Playback/Capture correctly.
* The point is [DVC] needs *Hardware* L/R, [MEM] needs *Software* L/R
*
* sL/R : software L/R
* hL/R : hardware L/R
* (*) : conversion timing
*
* Playback
* sL/R (*) hL/R hL/R hL/R hL/R hL/R
* [MEM] -> [SRC] -> [DVC] -> [CMD] -> [SSIU] -> [SSI] -> codec
*
* Capture
* hL/R hL/R hL/R hL/R hL/R (*) sL/R
* codec -> [SSI] -> [SSIU] -> [SRC] -> [DVC] -> [CMD] -> [MEM]
*/
if (rsnd_io_is_play(io)) {
struct rsnd_mod *src = rsnd_io_to_mod_src(io);