From mboxrd@z Thu Jan  1 00:00:00 1970
From: Fabio Estevam <festevam@gmail.com>
Subject: Re: [PATCH v2] ASoC: fsl_ssi: Fix channel swap on
	playback start
Date: Tue, 4 Apr 2017 14:12:33 -0300
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To: Arnaud Mouiche <arnaud.mouiche@invoxia.com>
Cc: "alsa-devel@alsa-project.org" <alsa-devel@alsa-project.org>, Sascha Hauer <kernel@pengutronix.de>, Timur Tabi <timur@tabi.org>, Caleb Crome <caleb@crome.org>, Nicolin Chen <nicoleotsuka@gmail.com>, Mark Brown <broonie@kernel.org>, Max Krummenacher <max.krummenacher@toradex.com>, Fabio Estevam <fabio.estevam@nxp.com>
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On Tue, Apr 4, 2017 at 8:38 AM, Fabio Estevam <festevam@gmail.com> wrote:

> I have the following SSI1 values (with the original 4.1-rc5 + pictrl patch):
>
> # cat /sys/kernel/debug/regmap/2028000.ssi/registers
> 00: 00000200
> 04: 00000000
> 10: 0000105b

Bits 6-5 (I2S_MODE) of register SCR are 10 of register SCR, which
means I2S slave mode.

The MX6 Reference Manual states:

"In I2S slave mode(SSI_SCR[6:5]=10), the following settings are
internally overridden by
the hardware:

Normal mode is selected (SSI_SCR[3]=0)
Tx frame sync length set to one-bit-long-frame (SSI_STCR[1]=1)
Rx frame sync length set to one-bit-long-frame (SSI_SRCR[1]=1)"

so I tried not to use the the one-bit-long-frame (since ENGcm06222 is
about bit length frame sync) override and changed it to I2S normal
mode instead:

--- a/sound/soc/fsl/fsl_ssi.c
+++ b/sound/soc/fsl/fsl_ssi.c
@@ -973,7 +973,7 @@ static int _fsl_ssi_set_dai_fmt(struct device *dev,
                        ssi_private->i2s_mode |= CCSR_SSI_SCR_I2S_MODE_MASTER;
                        break;
                case SND_SOC_DAIFMT_CBM_CFM:
-                       ssi_private->i2s_mode |= CCSR_SSI_SCR_I2S_MODE_SLAVE;
+                       ssi_private->i2s_mode |= CCSR_SSI_SCR_I2S_MODE_NORMAL;
                        break;
                default:
                        return -EINVAL;

and I do not get the channel swap anymore.

In what cases could we safely switch to I2S normal mode?

Thanks