Unverified Commit 8c363f61 authored by Kuninori Morimoto's avatar Kuninori Morimoto Committed by Mark Brown
Browse files

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: default avatarKuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Tested-by: default avatarYusuke Goda <yusuke.goda.sx@renesas.com>
Link: https://patch.msgid.link/875xd7yutm.wl-kuninori.morimoto.gx@renesas.com


Signed-off-by: default avatarMark Brown <broonie@kernel.org>
parent dc7473e6

sound/soc/renesas/rcar/msiof.c

+19 −0
Original line number Diff line number Diff line
@@ -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>