From: Kuninori Morimoto kuninori.morimoto.gx@renesas.com
SRC bypass mode is useful for debugging. This patch explains SRC bypass mode settings in comment
Signed-off-by: Kuninori Morimoto kuninori.morimoto.gx@renesas.com --- sound/soc/sh/rcar/scu.c | 45 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 45 insertions(+)
diff --git a/sound/soc/sh/rcar/scu.c b/sound/soc/sh/rcar/scu.c index 872a115..076aa71 100644 --- a/sound/soc/sh/rcar/scu.c +++ b/sound/soc/sh/rcar/scu.c @@ -40,6 +40,51 @@ struct rsnd_scu { * */
+/* + * How to use SRC bypass mode for debugging + * + * SRC has bypass mode, and it is useful for debugging. + * In Gen2 case, + * SRCm_MODE controls whether SRC is used or not + * SSI_MODE0 controls whether SSIU which receives SRC data + * is used or not. + * Both SRCm_MODE/SSI_MODE0 settings are needed if you use SRC, + * but SRC bypass mode needs SSI_MODE0 only. + * + * This driver request + * struct rsnd_scu_platform_info { + * u32 flags; + * u32 convert_rate; + * } + * + * rsnd_scu_hpbif_is_enable() will be true + * if flags had RSND_SCU_USE_HPBIF, + * and it controls whether SSIU is used or not. + * + * rsnd_scu_convert_rate() indicates + * above convert_rate, and it controls + * whether SRC is used or not. + * + * ex) doesn't use SRC + * struct rsnd_scu_platform_info info = { + * .flags = 0, + * .convert_rate = 0, + * }; + * + * ex) uses SRC + * struct rsnd_scu_platform_info info = { + * .flags = RSND_SCU_USE_HPBIF, + * .convert_rate = 48000, + * }; + * + * ex) uses SRC bypass mode + * struct rsnd_scu_platform_info info = { + * .flags = RSND_SCU_USE_HPBIF, + * .convert_rate = 0, + * }; + * + */ + #define rsnd_mod_to_scu(_mod) \ container_of((_mod), struct rsnd_scu, mod)