diff options
| author | Kuninori Morimoto <kuninori.morimoto.gx@renesas.com> | 2025-09-25 05:17:41 +0000 |
|---|---|---|
| committer | Mark Brown <broonie@kernel.org> | 2025-09-25 17:43:29 +0100 |
| commit | 8c363f61e5bcb92d5e88ca1b47be74be2683b212 (patch) | |
| tree | ec4fc9d7b481622ccaca00ea8d4473807cb63b6d | |
| parent | dc7473e6372ee36ff232af10c910ee3a8bad6447 (diff) | |
ASoC: renesas: msiof: Add note for The possibility of R/L opposite Capture
This driver is assuming MSIOF is used as Clock/Frame Consumer Mode, and
there is a case that some Codec (= Clock/Frame Provider) might output
Clock/Frame before setup MSIOF.
And, MSIOF will capture data without checking SYNC signal Hi/Low (= R/L).
This means, if MSIOF RXE bit was set as 1 in case of SYNC signal was Hi
(= R) timing, it will start capture data since next SYNC low signal (= L).
Because Linux assumes sound data is lined up as R->L->R->L->..., the data
R/L might be opposite.
The only solution in this case is start CLK/SYNC *after* MSIOF settings,
but it depends when and how Codec driver start it.
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Tested-by: Yusuke Goda <yusuke.goda.sx@renesas.com>
Link: https://patch.msgid.link/875xd7yutm.wl-kuninori.morimoto.gx@renesas.com
Signed-off-by: Mark Brown <broonie@kernel.org>
| -rw-r--r-- | sound/soc/renesas/rcar/msiof.c | 19 |
1 files changed, 19 insertions, 0 deletions
diff --git a/sound/soc/renesas/rcar/msiof.c b/sound/soc/renesas/rcar/msiof.c index df664800bf60..330b65b29597 100644 --- a/sound/soc/renesas/rcar/msiof.c +++ b/sound/soc/renesas/rcar/msiof.c @@ -46,6 +46,25 @@ * Setup both direction (Playback/Capture) in the same time. */ +/* + * [NOTE-R/L] + * + * The data of Captured might be R/L opposite. + * + * This driver is assuming MSIOF is used as Clock/Frame Consumer Mode, and there is a case that some + * Codec (= Clock/Frame Provider) might output Clock/Frame before setup MSIOF. It depends on Codec + * driver implementation. + * + * MSIOF will capture data without checking SYNC signal Hi/Low (= R/L). + * + * This means, if MSIOF RXE bit was set as 1 in case of SYNC signal was Hi (= R) timing, it will + * start capture data since next SYNC low singla (= L). Because Linux assumes sound data is lined + * up as R->L->R->L->..., the data R/L will be opposite. + * + * The only solution in this case is start CLK/SYNC *after* MSIOF settings, but it depends when and + * how Codec driver start it. + */ + #include <linux/module.h> #include <linux/of.h> #include <linux/of_dma.h> |